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Hearing aids are commonly fit with ear canals partially or fully open-a condition that increases the risk of acoustic feedback. Feedback limits the audiometric fitting range of devices by limiting usable gain. To guide clinical decision making and device selection, we developed the Peak Height Insertion Gain (PHIG) method to detect feedback spikes in the short-term insertion gain derived from audio recordings. Using a manikin, 145 audio recordings of a speech signal were obtained from seven hearing aids. Each hearing aid was programmed for a moderate high-frequency hearing loss with systematic variations in frequency response, gain, and feedback suppression; this created audio recordings that varied the presence and strength of feedback. Using subjective ratings from 13 expert judges, the presence of feedback was determined and then classified according to its temporal and tonal qualities. These classifications were used to optimize parameters for two versions of the PHIG method based on global and local analyses. When specificity was fixed at 0.95, the sensitivity of the global analysis was 0.86 and increased to 0.95 when combined with the local analysis. Without compromising performance, a clinically expedient version of the PHIG method can be obtained using only a single measurement.

Background Hearing aid fitting guidelines recommend real ear measures (REM) to verify hearing aid performance. Unfortunately, approximately 70 to 80% of clinicians do not use REM, but instead download manufacturer first-fit. Studies report differences in performance between first-fit and programmed-fit with greatest differences in the higher frequencies. Recently, hearing aid and real ear analyzer (REA) manufacturers allow REA communication with hearing aid software feature to automatically program hearing aids to target. Little research is available reporting the accuracy of this feature. Purpose The aim of the study is to examine whether differences exist at 50, 65, and 80 dB SPL between two ReSound first-fit formulae (Audiogram+ and NAL-NL2) using ReSound AutoREM and Aurical NAL-NL2 Research Design The study design is of repeated measure type. Study Sample The study sample includes 48 ears. Data Collection and Analysis For the two fitting formulae, AutoREM real ear insertion gain (REIG) was measured at 50, 65, and 80 dB SPL and compared with measures from Aurical NAL-NL2. Results Mean AutoREM REIG for ReSound NAL-NL2 was 3 to 8 dB below Aurical NAL-NL2 for 50 dB SPL, within 1 to 3 dB for 65 dB SPL and 1 to 5 dB above for 80 dB SPL. Mean AutoREM REIG for Audiogram + was 1 to 12 dB below Aurical NAL-NL2 for 50 dB SPL, within 2 to 5 dB for 65 dB SPL and 1 to 7 dB above NAL-NL2 for 80 dB SPL. Conclusion Relative to the Aurical NAL-NL2, AutoREM REIG50 for Audiogram + and ReSound NAL-NL2 was lower. Relative to the Aurical NAL-NL2, AutoREM REIG65 for Audiogram + was higher at 1,000 Hz and lower at 4,000 to 6,000 Hz and for ReSound NAL-NL2 it was lower at 500 Hz and 4,000 Hz and higher at 3,000 Hz. Relative to the Aurical NAL-NL2, AutoREM REIG80 for Audiogram + was higher at 500 to 3,000 Hz and 6,000 Hz and ReSound NAL-NL2 was higher at 500 to 6,000 Hz. Because of wide intersubject variability clinicians should continue to use REM as a “check and balance” when using AutoREM.

This paper analytically investigates the dynamic interaction of two neighboring tunnels in the saturated soil. The twin tunnels are simulated using the Flugge shell theory, and the surrounding soil is modelled by the Biot’s theory. The solution for cylindrical waves in saturated porous media is derived by applying the potential decomposition. The addition theorem is subsequently introduced to translate cylindrical waves, thereby satisfying the boundary conditions at the interfaces between the twin tunnels and saturated soil. Numerical examples are presented to analyze soil vibrations under different loading conditions calculated by different tunnel models. The neighboring tunnels have strong dynamic interaction, resulting in the insertion gain up to ± 20 dB. It is recommended to account for the interaction between neighboring tunnels when calculating the vibrations from underground railways.

The American Speech-Language-Hearing Association (ASHA) and American Academy of Audiology (AAA) have created Best Practice Guidelines for fitting hearing aids to adult patients. These guidelines recommend using real-ear measures (REM) to verify that measured output/gain of hearing aid(s) match a validated prescriptive target. Unfortunately, approximately 70–80% of audiologists do not routinely use REM when fitting hearing aids, instead relying on a manufacturer default “first-fit” setting. This is problematic because numerous studies report significant differences in REM between manufacturer first-fit and the same hearing aids using a REM or programmed-fit. These studies reported decreased prescribed gain/output in the higher frequencies for the first-fit compared with the programmed fit, which are important for recognizing speech. Currently, there is little research in peer-reviewed journals reporting if differences between hearing aids fitted using a manufacturer first-fit versus a programmed-fit result in significant differences in speech recognition in quiet, noise, and subjective outcomes.To examine if significant differences were present in monosyllabic word and phoneme recognition (consonant-nucleus-consonant; CNC) in quiet, sentence recognition in noise (Hearing in Noise Test; HINT), and subjective outcomes using the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Speech, Spatial and Qualities of Hearing (SSQ) questionnaires between hearing aids fit using one manufacturer’s first-fit and the same hearing aids with a programmed-fit using REM to National Acoustic Laboratories Nonlinear Version 2 (NAL-NL2) prescriptive target.A double-blind randomized crossover design was used. Throughout the study, one investigator performed all REM whereas a second investigator measured speech recognition in quiet, noise, and scored subjective outcome measures.Twenty-four adults with bilateral normal sloping to moderately severe sensorineural hearing loss with no prior experience with amplification.The hearing aids were fit using the proprietary manufacturer default first-fit and a programmed-fit to NAL-NL2 using real-ear insertion gain measures. The order of the two fittings was randomly assigned and counterbalanced. Participants acclimatized to each setting for four weeks and returned for assessment of performance via the revised CNC word lists, HINT, APHAB, and SSQ for the respective fitting.(1) A significant median advantage of 15% (p < 0.001; 95% CI: 9.7–24.3%) for words and 7.7% (p < 0.001; 95% CI: 5.9–10.9%) for phonemes for the programmed-fit compared with first-fit at 50 dB sound pressure level (SPL) and 4% (p < 0.01; 95% CI: 1.7–6.3%) for words at 65 dB SPL; (2) No significant differences for the HINT reception threshold for sentences (RTS); (3) A significant median advantage of 4.2% [p < 0.04; 95% confidence interval (CI): −0.6–13.2%] for the programmed-fit compared with the first-fit for the background noise subscale problem score for the APHAB; (4) No significant differences on the SSQ.Improved word and phoneme recognition for soft and words for average speech in quiet were reported for the programmed-fit. Seventy-nine percent of the participants preferred the programmed-fitting versus first-fit. Hearing aids, therefore, should be verified and programmed using REM to a prescriptive target versus no verification using a first-fit.

Unilateral auditory deprivation or stimulation can induce changes in loudness and modify the sound level required to elicit the acoustic reflex. This has been explained in terms of a change in neural response, or gain, for a given sound level. However, it is unclear if these changes are driven by the asymmetry in auditory input or if they will also occur following bilateral changes in auditory input. The present study used a cross-over trial of unilateral and bilateral amplification to investigate changes in the acoustic reflex thresholds (ARTs) and the auditory brainstem response (ABR) in normal hearing listeners. Each treatment lasted 7 days and there was a 7-day washout period between the treatments. There was no significant change in the ART or ABR with either treatment. This null finding may have occurred because the amplification was insufficient to induce experience-related changes to the ABR and ART. Based on the null findings from the present study, and evidence of a change in ART in previous unilateral hearing aid use in normal hearing listeners, the threshold to trigger adaptive changes appears to be around 5 days of amplification with real ear insertion gain greater than 13-17 dB.

This paper presents the implementation of a broadband quasi-circulator through a cascading distributed balun using a 90-nm CMOS process. The isolation, $\vert \text{S}31\vert $ , of the proposed three-port quasi-circulator can be acquired through the phase cancelation technique, by connecting an additional distributed amplifier in parallel between ports 1 and 3. The thorough analysis based on an eight-port chain matrix and scattering matrix is presented for refining the circuit parameters in the initial design. Measured results show that the proposed quasi-circulator attains a broad operation bandwidth ranging from 10 to 67 GHz. Moreover, the quasi-circulator also has good insertion gain of 0.5 to 4.8 dB, as well as isolation $\vert \text{S}31\vert $ , which is better than 23 dB. Consequently, the proposed quasi-circulator delivers wide bandwidth performance, good port-to-port isolations, good insertion gain, and high linearity based on the cascading distributed balun with phase cancelation technique.

In this article, a compact W-band differential I---Q phase shifter is designed and implemented using 28-nm CMOS technology. The phase shifter is capable of achieving phase shifts ranging from 45° to 315° with a resolution of 90°. The design employs transmission-line baluns for creating a differential signal, Gilbert-cell-type active switches for generating 0° and 180° phase shifts and a 90° differential hybrid for obtaining differential I---Q signals. The hybrid is developed using capacitive-loaded slow-wave differential lines, thereby making it 75 % smaller than a conventional 90° hybrid. Furthermore, the modelling of a slow-wave differential line for odd-mode and even-mode propagation is explained. The phase shifter exhibits 12 dB of insertion loss, and the root-mean-square (RMS) gain and phase error are 0.55 dB and 16.6°, respectively, at 100 GHz. The total power consumption is 39 mW when using a 1-V supply. The chip size of the implemented design is 0.48 mm2 including the probing pads. The phase shifter design is further modified by replacing the baluns with single-stage differential buffer amplifiers to mitigate the signal loss. This modified version of the design shows +1 dB insertion gain with a total power consumption of 122.9 mW from a 1-V supply and realized at 0.565 mm2. A 13-dB gain improvement is obtained from the modified version and the measured RMS gain and phase error are 1.5 dB and 13°, respectively, at 100 GHz. After redesigning the layout, a minimum RMS phase error of 1.7° is expected in the simulations.

Purpose A model was developed to examine variables that influence signal-to-noise ratio (SNR) at the tympanic membrane (TM) when using a hearing aid (HA) and frequency modulated (FM) system. The model was used to explore how HA coupling influences SNR. Method To generate the model, HA output was measured in a coupler. Known coupler to real-ear transformations and known values for vent (gain) loss as a function of coupling were also used. The model was verified by measuring sound pressure level (SPL) at the TM in 6 ears. Results The model predicts similar overall SNRs at the TM regardless of coupling method when HA and FM microphones are active. The primary difference in SNR is in the low frequencies and depends on the amount of low frequency insertion gain and the noise levels at the HA and FM microphones. Conclusions A model was developed to explore how complex variables contribute to SNR at the TM. One variable, HA coupling, is predicted to have only a minimal effect on SNR at the TM when there is HA gain. Further studies will be needed to assess the real-world effectiveness of an FM system coupled to an open- versus closed-fit HA.

Planar electromagnetic interference (EMI) filters are widely used to restrain the conducted EMI of switching power supplies. Such filters are characterized by small size, low parasitic parameters, and better high-frequency performance than the passive discrete EMI filter. However, EMI filter performance cannot be exactly predicted by using existing methods. Therefore, this paper proposes a method to use scattering parameters (S-parameters) for the measurement of EMI filter performance. A planar EMI filter sample is established. From this sample, the relationship between S-parameters and insertion gain (IG) of EMI filter is derived. To determine the IG under different impedances, the EMI filter is theoretically calculated and practically measured. The differential structure of the near-field coupling model is also deduced, and the IG is calculated under standard impedance conditions. The calculated results and actual measurements are compared to verify the feasibility of the theory.

© 2014 Elsevier Ltd. The numerical prediction of vibrations in buildings due to railway traffic is a complicated problem where wave propagation in the soil couples the source (railway tunnel or track) and the receiver (building). This through-soil coupling is often neglected in state-of-the-art numerical models in order to reduce the computational cost. In this paper, the effect of this simplifying assumption on the accuracy of numerical predictions is investigated. A coupled finite element-boundary element methodology is employed to analyze the interaction between a building and a railway tunnel at depth or a ballasted track at the surface of a homogeneous halfspace, respectively. Three different soil types are considered. It is demonstrated that the dynamic axle loads can be calculated with reasonable accuracy using an uncoupled strategy in which through-soil coupling is disregarded. If the transfer functions from source to receiver are considered, however, large local variations in terms of vibration insertion gain are induced by source-receiver interaction, reaching up to 10 dB and higher, although the overall wave field is only moderately affected. A global quantification of the significance of through-soil coupling is made, based on the mean vibrational energy entering a building. This approach allows assessing the common assumption in seismic engineering that source-receiver interaction can be neglected if the distance between source and receiver is sufficiently large compared to the wavelength of waves in the soil. It is observed that the interaction between a source at depth and a receiver mainly affects the power flow distribution if the distance between source and receiver is smaller than the dilatational wavelength in the soil. Interaction effects for a railway track at grade are observed if the source-receiver distance is smaller than six Rayleigh wavelengths. A similar trend is revealed if the passage of a freight train is considered. The overall influence of dynamic through-soil coupling in terms of power flow remains limited to 2 dB, but the insertion gain at particular locations can easily reach 10 dB. This is of the same order of magnitude as other sources of uncertainty in the numerical prediction of railway induced vibrations; this should hence be accounted for when performing vibration predictions. ispartof: Journal of Sound and Vibration vol:333 issue:12 pages:2520-2538 status: published

Background: In the past, bilateral contralateral routing of signals (BICROS) amplification incorporated omnidirectional microphones on the transmitter and receiver sides and some models utilized noise reduction (NR) on the receiver side. Little research has examined the performance of BICROS amplification in background noise. However, previous studies examining contralateral routing of signals (CROS) amplification have reported that the presence of background noise on the transmitter side negatively affected speech recognition. Recently, NR was introduced as a feature on the receiver and transmitter sides of BICROS amplification, which has the potential to decrease the impact of noise on the wanted speech signal by decreasing unwanted noise directed to the transmitter side. Purpose: The primary goal of this study was to examine differences in the reception threshold for sentences (RTS in dB) using the Hearing in Noise Test (HINT) in a diffuse listening environment between unaided and three aided BICROS conditions (no NR, mild NR, and maximum NR) in the Tandem 16 BICROS. A secondary goal was to examine real-world subjective impressions of the Tandem 16 BICROS compared to unaided. Research Design: A randomized block repeated measures single blind design was used to assess differences between no NR, mild NR, and maximum NR listening conditions. Study Sample: Twenty-one adult participants with asymmetric sensorineural hearing loss (ASNHL) and experience with BICROS amplification were recruited from Washington University in St. Louis School of Medicine. Data Collection and Analysis: Participants were fit with the National Acoustic Laboratories’ Nonlinear version 1 prescriptive target (NAL-NL1) with the Tandem 16 BICROS at the initial visit and then verified using real-ear insertion gain (REIG) measures. Participants acclimatized to the Tandem 16 BICROS for 4 wk before returning for final testing. Participants were tested utilizing HINT sentences examining differences in RTS between unaided and three aided listening conditions. Subjective benefit was determined via the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire between the Tandem 16 BICROS and unaided. A repeated measures analysis of variance (ANOVA) was utilized to analyze the results of the HINT and APHAB. Results: Results revealed no significant differences in the RTS between unaided, no NR, mild NR, and maximum NR. Subjective impressions using the APHAB revealed statistically and clinically significant benefit with the Tandem 16 BICROS compared to unaided for the Ease of Communication (EC), Background Noise (BN), and Reverberation (RV) subscales. Conclusions: The RTS was not significantly different between unaided, no NR, mild NR, and maximum NR. None of the three aided listening conditions were significantly different from unaided performance as has been reported for previous studies examining CROS hearing aids. Further, based on comments from participants and previous research studies with conventional hearing aids, manufacturers of BICROS amplification should consider incorporating directional microphones and independent volume controls on the receiver and transmitter sides to potentially provide further improvement in signal-to-noise ratio (SNR) for patients with ASNHL.

Background: Hearing aid prescriptive recommendations for hearing losses having a conductive component have received less clinical and research interest than for losses of a sensorineural nature; as a result, much variation remains among current prescriptive methods in their recommendations for conductive and mixed hearing losses (Johnson and Dillon, 2011). Purpose: The primary intent of this brief clinical note is to demonstrate differences between two algebraically equivalent expressions of hearing loss, which have been approaches used historically to generate a prescription for hearing losses with a conductive component. When air and bone conduction thresholds are entered into hearing aid prescriptions designed for nonlinear hearing aids, it was hypothesized that that two expressions would not yield equivalent amounts of prescribed insertion gain and output. These differences are examined for their impact on the maximum power output (MPO) requirements of the hearing aid. Subsequently, the MPO capabilities of two common behind-the-ear (BTE) receiver placement alternatives, receiver-in-aid (RIA) and receiver-in-canal (RIC), are examined. Study Samples: The two expressions of hearing losses examined were the 25% ABG + AC approach and the 75% ABG + BC approach, where ABG refers to air-bone gap, AC refers to air-conduction threshold, and BC refers to bone-conduction threshold. Example hearing loss cases with a conductive component are sampled for calculations. The MPO capabilities of the BTE receiver placements in commercially-available products were obtained from hearing aids on the U.S. federal purchasing contract. Results: Prescribed gain and the required MPO differs markedly between the two approaches. The 75% ABG + BC approach prescribes a compression ratio that is reflective of the amount of sensorineural hearing loss. Not all hearing aids will have the MPO capabilities to support the output requirements for fitting hearing losses with a large conductive component particularly when combined with significant sensorineural hearing loss. Generally, current RIA BTE products have greater output capabilities than RIC BTE products. Conclusions: The 75% ABG + BC approach is more appropriate than the 25% ABG + AC approach because the latter approach inappropriately uses AC thresholds as the basis for determining the compression ratio. That is, for hearing losses with a conductive component, the AC thresholds are not a measure of sensorineural hearing loss and cannot serve as the basis for determining the amount of desired compression. The Australian National Acoustic Laboratories has been using the 75% ABG + BC approach in lieu of the 25% ABG + AC approach since its release of the National Acoustic Laboratories—Non-linear 1 (NAL-NL1) prescriptive method in 1999. Future research may examine whether individuals with conductive hearing loss benefit or prefer more than 75% restoration of the conductive component provided adequate MPO capabilities to support such restoration.

The last decade has offered a multitude of instant fi t coupling systems to be fi tted with behind-the-ear (BTE) hearing aids. The impact of these designs on the reliability of real ear measurements (REMs) has not been reported. The purpose of this study was to obtain REM reliability data for instant fi t coupling systems. Design: REM reliability data was obtained for four different instant-fi t coupling systems and for standard size 13 tubing and custom earmolds. REMs were performed for all fi ve coupling systems two times and by two examiners. Study sample: Ten normal-hearing individuals (20 ears) served as participants. Results: The REM test-retest reliability is high for the four instant fi t coupling systems as well as for the custom earmolds. The REM inter-examiner reliability is high for three of the four instant fi t coupling systems. Conclusions: Carrying out REMs with instant fi t coupling systems appears to be fundamentally no different than performing REMs with conventional hearing aids. For either, care should be taken in probe tube placement in terms of insertion depth and maintaining the probe tube placement, and other best practices regarding test environment and test setup should be observed.

Preferences between low delays and phase-frequency responses of behind-the-ear, open-canal hearing aids were investigated with acoustic conditions deemed sensitive to delay effects by normal-hearing listeners.Hearing aids with the following selectable delay and phase response options were fitted at low insertion gain: (1) 1.4 ms delay, minimum phase; (2) 3.4 ms delay, minimum phase; and (3) 3.4 ms delay, linear phase. Blind paired comparisons were made between processing options and between each option and a muted hearing-aid output with two music stimuli. The three alternative forced choice responses were "Slightly prefer", "Prefer", or "Strongly prefer".Twelve hearing-impaired musicians.At the 3.4-ms delay, the minimum-phase response was significantly preferred to the linear-phase response for one music sample and vice-versa for the other sample with a sign test (p0.04) but not a Wilcoxon signed rank test that accounted for the low preference strength. Preferences between all other processing conditions were not significant.In acoustic conditions sensitive to delay effects, delays of 1.4 or 3.4 ms were either not detected or no less preferable than no delayed aided signal. It is unclear whether different phase-frequency responses may be preferred with different music stimuli.

Background: Prescriptive methods have been at the core of modern hearing aid fittings for the past several decades. Every decade or so, there have been revisions to existing methods and/or the emergence of new methods that become widely used. In 2001 Byrne et al provided a comparison of insertion gain for generic prescriptive methods available at that time. Purpose: The purpose of this article was to compare National Acoustic Laboratories—Non-linear 1 (NAL-NL1), National Acoustic Laboratories—Non-linear 2 (NAL-NL2), Desired Sensation Level Multistage Input/Output (DSL m[i/o]), and Cambridge Method for Loudness Equalization 2—High-Frequency (CAMEQ2-HF) prescriptive methods for adults on the amplification characteristics of prescribed insertion gain and compression ratio. Following the differences observed in prescribed insertion gain among the four prescriptive methods, analyses of predicted specific loudness, overall loudness, and bandwidth of cochlear excitation and effective audibility as well as speech intelligibility of the international long-term average speech spectrum (ILTASS) at an average conversational input level were completed. These analyses allow for the discussion of similarities and differences among the present-day prescriptive methods. Research Design: The impact of insertion gain differences among the methods is examined for seven hypothetical hearing loss configurations using models of loudness perception and speech intelligibility. Study Sample: Hearing loss configurations for adults of various types and degrees were selected, five of which represent sensorineural impairment and were used by Byrne et al; the other two hearing losses provide an example of mixed and conductive impairment. Data Collection and Analysis: Prescribed insertion gain data were calculated in 1/3-octave frequency bands for each of the seven hearing losses from the software application of each prescriptive method over multiple input levels. The insertion gain data along with a diffuse field-to-eardrum transfer function were used to calculate output levels at the eardrums of the hypothetical listeners. Levels of hearing loss and output were then used in the Moore and Glasberg loudness model and the ANSI S3.5-1997 Speech Intelligibility Index model. Results: NAL-NL2 and DSL m[i/o] provided comparable overall loudness of approximately 8 sones for the five sensorineural hearing losses for a 65 dB SPL ILTASS input. This loudness was notably less than that perceived by a normal-hearing person for the same input signal, 18.6 sones. NAL-NL2 and DSL m[i/o] also provided comparable predicted speech intelligibility in quiet and noise. CAMEQ2-HF provided a greater average loudness, similar to NAL-NL1, with more high-frequency bandwidth but no significant improvement to predicted speech intelligibility. Conclusions: Definite variation in prescribed insertion gain was present among the prescriptive methods. These differences when averaged across the hearing losses were, by and large, negligible with regard to predicted speech intelligibility at normal conversational speech levels. With regard to loudness, DSL m[i/o] and NAL-NL2 provided the least overall loudness, followed by CAMEQ2-HF and NAL-NL1 providing the most loudness. CAMEQ2-HF provided the most audibility at high frequencies; even so, the audibility became less effective for improving speech intelligibility as hearing loss severity increased.

Nascent membrane proteins typically insert in a sequential fashion into the membrane via a protein-conducting channel, the Sec translocon. How this process occurs is still unclear, although a thermodynamic partitioning between the channel and the membrane environment has been proposed. Experiment- and simulation-based scales for the insertion free energy of various amino acids are, however, at variance, the former appearing to lie in a narrower range than the latter. Membrane insertion of arginine, for instance, requires 14–17 kcal/mol according to molecular dynamics simulations, but only 2–3 kcal/mol according to experiment. We suggest that this disagreement is resolved by assuming a two-stage insertion process wherein the first step, the insertion into the translocon, is energized by protein synthesis and, therefore, has an effectively zero free-energy cost; the second step, the insertion into the membrane, invokes the translocon as an intermediary between the fully hydrated and the fully inserted locations. Using free-energy perturbation calculations, the effective transfer free energies from the translocon to the membrane have been determined for both arginine and leucine amino acids carried by a background polyleucine helix. Indeed, the insertion penalty for arginine as well as the insertion gain for leucine from the translocon to the membrane is found to be significantly reduced compared to direct insertion from water, resulting in the same compression as observed in the experiment-based scale.

This paper analyzes the transformation between differential-mode and common-mode noises due to the unbalance of noise sources and electromagnetic interference filters in power electronics circuits. Both insertion gain and electromagnetic interference measurements prove the analysis.

This paper presents the design of a 60 GHz phase shifter integrated with a low-noise amplifier (LNA) and power amplifier (PA) in a 65 nm CMOS technology for phased array systems. The 4-bit digitally controlled RF phase shifter is based on programmable weighted combinations of I/Q paths using digitally controlled variable gain amplifiers (VGAs). With the combination of an LNA, a phase shifter and part of a combiner, each receiver path achieves 7.2 dB noise figure, a 360° phase shift range in steps of approximately 22.5°, an average insertion gain of 12 dB at 61 GHz, a 3 dB-bandwidth of 5.5 GHz and dissipates 78 mW. Consisting of a phase shifter and a PA, one transmitter path achieves a maximum output power of higher than +8.3 dBm, a 360° phase shift range in 22.5° steps, an average insertion gain of 7.7 dB at 62 GHz, a 3 dB-bandwidth of 6.5 GHz and dissipates 168 mW.

When hearing aid gain is prescribed by software, gain is calculated based on the average acoustics for the age of patient, gender, mold type, and so on. The acoustics of the individual's ear often vary from the average values, so there will be a mismatch between the prescribed gain and the real-ear gain. Real-ear measurement can be used to verify the gain and adjust it to meet targets, but the quality of the match will be limited by the number of channels and the flexibility of the hearing aid. A potential way to improve this process is to generate a filter that compensates for variations in real-ear insertion gain due to individual ear acoustics. Such a filter could be included in the processing path of a digital hearing aid. This article describes how such a filter can be generated using the windowing method, and the principle is demonstrated in a real ear. The approach requires communication between the real-ear measurement and hearing aid programming software. A finite impulse response filter with group delay just over 2 ms matched insertion gain to target values within the acceptable tolerance defined by British Society of Audiology guidelines.

The present study investigated the possible use of the auditory steady state response (ASSR) technique in hearing aid fitting. The relationship between the real ear insertion gain (REIG) and ASSR gain (unaided ASSR threshold vs. aided ASSR threshold) was examined. Thirty subjects with mild to moderately severe sensorineural hearing loss with age range of 15 years to 50 years (mean age 32 years) participated in the study. Based on the degree, configuration and type of hearing loss, two digital BTE hearing aids were preselected. For each subject insertion gain and ASSR gain were measured at 500 Hz, 1 kHz, 2 kHz and 4 kHz. The hearing aid that best matched with the target curve during insertion gain measurement was selected for the ASSR measurement. ASSR gain and REIG were highly correlated with significance values p < .05. Paired sample t tests revealed that there was no significant difference at all test frequencies. The ASSR technique shows great promise in hearing aid fitting for those who can not reliably respond on behavioral testing.

Real-ear measurements using the modified pressure method with concurrent (real-time) equalization can be inaccurate, when amplified sound leaks out of the ear canal and reaches the reference microphone. In such situations the reference microphone will detect an increased sound level and reduce the output of the loudspeaker to maintain the desired level. The risk of having errors due to leaks increases if digital feedback suppression (DFS) is used, thus achieving higher feedback-free gain levels. The following hypotheses were tested: a) using the concurrent equalization method for fitting hearing instruments with DFS may result in underestimated real-ear insertion gain (especially when using open fittings) and b) as the benefit of the DFS system increases, this error also increases. Real-ear measurements were carried out in twenty-one subjects using the modified pressure method with stored equalization as well as with concurrent equalization. The results of the study supports both hypotheses. As a consequence it is recommended to use a stored equalization method for real-ear measurements of hearing instruments with DFS and open fitting.

A predistortion-type equi-path linearizer is created for a radio-on-fiber system based on wide-band code division multiple access; its main benefit is its simple optical circuit configuration. Experiments show that the phase difference between the carrier and third-order intermodulation (IM3) component of the laser diodes (LDs) is shifted by around 90/spl deg/ from that of the RF amplifier. To our knowledge, this is the first report to describe this phase shift, which is observed with both Fabry-Perot and distributed-feedback LDs. To counter this shift, we use additional phase shifters. The proposed design places a pre-amplifier between the linearizer and LD for lower power consumption and better insertion gain at the linearizer. Experimental and calculated results agree well, and more than 20-dB improvement in the IM3 components is obtained over the bandwidth of 60 MHz. The linearizer works well in the temperature range of 10/spl deg/C to 40/spl deg/C with a simple control circuit.

The time course of changes in perceived sound quality after hearing instrument fitting has not been studied systematically It is possible, for example, that patients may object to additional high frequency gain when fitted, but not after a period of auditory acclimatisation. The aim of this study was to utilise sound quality judgements to compare two frequency responses in new users at 4-week intervals over a 24-week post-fitting period. The null hypothesis was that there would be no change in sound quality judgements over time. A total of 16 elderly subjects were fitted monaurally with the same model of linear, programmable hearing instrument. This was set to a standard response that provided 26-29 dB of real-ear insertion gain at 2000 4000 Hz. This program was worn by the subjects for the duration of the study. All subjects reported greater than four hours of daily use. The alternative response which was used in a paired comparison paradigm, provided a mean gain reduction of 3, 8, 13, and 16 dB at 2000, 3000, 4000 and 6000 Hz, respectively. Subjects compared the standard and the alternative responses for sound quality along dimensions of comfort, clarity, and overall preference while listening to running speech presented in quiet, steady noise, and speech babble. At the time of fitting there was a small preference for the standard response when judging clarity, but the alternative response was preferred for comfort and preferred overall. Repeated-measures analysis of variance (ANOVA) for each quality dimension did not reveal any statistically significant change over time. It is concluded that this pattern of preference is unaffected by acclimatisation to amplification, at least over the initial 24 weeks of instrument use.

This paper describes the outcome of a clinical trial of a low-cost high power compression behind-the ear-hearing aid (BTE-HA), performed in order to assure the quality of the product. Twenty-one experienced HA users, 14 males and 7 females at a median age of 77 years, (range 50–86 years) were recruited among persons fitted with HAs within a period of 6–12 months prior to recruitment. Seventeen had been fitted previously with binaural DSP-HAs, whereas four had a monaural fitting with analogue HAs. All subjects had a hearing loss >50 db at 2 kHz. Validation of the fitting according to the NAL-R prescription or POGO prescription was performed by insertion gain measurements, showing that the HA meets the frequency and amplification characteristics required according to an individual hearing loss. The immediate improvement in SRS in quiet on an individual basis was median 52% (range 8–96) and in background noise (S/N=5 dB) median 43% (range 0–76). A comparison between the benefits obtained with the test-HA and...

Closed-set word tests can be implemented with or without trial-by-trial visual feedback. Feedback is considered to increase subject motivation yet its influence on performance is unknown. The aim of this study was to compare performance on the Four Alternative Auditory Feature (FAAF) test with and without visual feedback over a 24-week period following fitting of a hearing aid. A total of 32 elderly subjects were recruited as new users and fitted monaurally with the same model of linear, programmable hearing aid that provided in excess of 20 dB insertion gain at 2-4 kHz. Half of the subjects were provided with visual feedback. In these subjects, mean performance increased by 5% across the study period. The improvement in performance over time was statistically significant on analysis of variance (p < 0.05). Mean performance did not increase in the remaining subjects who were not provided with feedback. If closed-set word tests are to be used with visual feedback to measure changes over time, the potentially confounding effects of practice must be controlled carefully. Alternatively, omitting feedback leads to simpler experimental designs.

An ultra wideband (UWB) quasi-circulator implemented with distributed amplifiers using the 90 nm complementary metal-oxide-semiconductor (CMOS) technology is presented. The proposed quasi-circulator is composed of two distributed amplifiers and two Lange couplers to attain UWB performance at 14 to 67 GHz. Good insertion gain of 4.3 dB to -3.5 dB, low noise figure of 7.1 to 12.6 dB, and good isolation characteristic of |S31| better than 20 dB can be obtained. Using the distributed amplifier technique, the proposed quasi-circulator offers significant advantages of broad operation bandwidth, high isolation, low noise figure, and good insertion gain.

In July 2001 the World Health Organization (WHO) launched their "Guidelines for hearing aids and services for developing countries". The objective of this study was to evaluate the clinical outcome of an analogue, low-cost, behind-the-ear hearing aid (BTE-HA) that met the minimum technical requirements outlined by the WHO.A total of 25 subjects (17 males, 8 females; median age 74 years; range 50-86 years) were recruited among patients referred for audiological evaluation who consented to participate in the trial. All subjects had a hearing loss ofor = 60 dB HL at 2 kHz, were mobile and mentally unimpaired; 13 were experienced users of HAs, 3 suffered from mixed conductive/sensorineural hearing impairment (HI) and the remainder had pure sensorineural HI. Based on pure-tone, speech and impedance audiometry the BTE-HAs were fitted, using the National Acoustic Laboratories-R (NAL-R) prescription rule, 21 binaurally and 4 monaurally. All fittings were validated by insertion gain measurements, and the immediate benefit was measured by means of the speech recognition score in background noise (SRSN; signal:noise ratio = 10 dB) without and with the HA. After a 6-week trial period a structured interview based on the International Outcome Inventory for Hearing Aids (IOI-HAs) was performed.The results showed that the amplification of the HA deviated significantly from the NAL-R target at all frequencies, giving significantly more amplification at 500 and 1000 Hz despite maximum bass-cut, whenever relevant, and significantly less amplification as required at 2, 3 and 4 kHz. The median SRSN without HA was 48% (range 0-96%), which improved significantly to 80% (range 24-100%) with HA. The median individual difference in SRSN without and with HA was 20% (range 0-72%). The total IOI-HA score with the test HA was 4.1 (range 2.6-4.6), showing that it offered subjectively high satisfaction and reduction in limitations of activity.The low-cost HA: (i) provides benefit to the hearing-impaired person; (ii) offers poor amplification in the high frequencies; and (iii) gives subjective satisfaction similar to that for modern available HAs.

Hypothesis The aim of this review is to present 19th century mechanical hearing devices that were designed for concealment or camouflage. Background Extensive literature, past and current, along with museum catalogs, trade catalogs, and advertisements, were examined to identify mechanical devices designed for concealment. Methods Several mechanical devices were selected for acoustic gain measurements. Measurements were made in an anechoic chamber using a Knowles Electronics Manikin for Acoustic Research fitted with a Zwislocki coupler and a pressure microphone in the right ear. One-third-octave bands of noise were presented via a KLH Model 6 loudspeaker placed at a distance of 2.23 m on-axis. The sound level at the ear of the Knowles Electronics Manikin for Acoustic Research was recorded with and without the device in place. Results A wide variety of 19th century hearing devices designed for concealment were identified. Some hearing devices, such as fans, parasols, lorgnettes, water canteens, walking sticks, chairs/thrones, hats, and books, were concealed within everyday items. Other hearing devices, such as artificial conchae, bouquet holders, and hair and beard receptors, wereconcealed on the person. The insertion gain of a representative concealed device, the Aurolese Phone, averaged approximately 3.5 dB in the range of frequencies most relevant for speech communication. Conclusions The ingenuity behind the design of 19th century mechanical hearing devices created for concealment or camouflage is to be commended. For the Aurolese Phone, some acoustic benefit was possible despite design constraints imposed by its concealed nature.

The aided threshold (and functional gain) has been discussed in the context of linear hearing aids since the early 1960s. The use of nonlinear hearing aids, however, could change the meaningfulness of this verification tool because of their unique characteristics. The interpretation of the aided threshold (and functional gain) as it pertains to linear and nonlinear hearing aids is reviewed. Also discussed are the ideas of an optimal aided threshold, factors that may affect its magnitude, and a comparison between functional gain and insertion gain measures. Finally, how to improve the accuracy of the aided thresholds (and functional gain) through the use of in-situ unaided threshold measurements is discussed.

Wind noise was measured in four behind-the-ear hearing instruments with different microphone openings. A silent airflow of 7 m/s was directed toward the ear of a Kemar head and the resulting wind noise was measured. The amplification was set to an insertion gain of 35 dB at 1.6 kHz. The wind noise amplitude at the position of the drum ranged from 84 to 97 dB(A). The hearing instrument with a partially covered microphone entrance proved best, whereas one with an open microphone entrance had the poorest performance. A reduction in wind noise of 6-17 dB could be achieved in all hearing instruments by using a simple windscreen made of Styrofoam. The windscreen affected the frequency response by less than 2 dB. By subtracting the insertion gain from the wind noise, an equivalent wind noise could be presented as a function of frequency. A considerable difference was found between the wind noise sensitivity in different hearing instruments. All could be improved by a windscreen without adversely affecting the frequency response.

An active image-rejection filter is presented in this paper, which applies actively coupled passive resonators. The filter has very low noise and high insertion gain, which may eliminate the use of a low-noise amplifier (LNA) in front-end applications. The GaAs monolithic-microwave integrated-circuit (MMIC) chip area is 3.3 mm/sup 2/. The filter has 12-dB insertion gain, 45-dB image rejection, 6.2-dB noise figure, and dissipates 4.3 mA from a 3-V supply. An MMIC mixer is also presented. The mixer applies two single-gate MESFETs on a 2.2-mm/sup 2/ GaAs substrate. The mixer has 2.5-dB conversion gain and better than 8-dB single-sideband (SSB) noise figure with a current dissipation of 3.5 mA applying a single 5-V supply. The mixer exhibits very good local oscillator (LO)/RF and LO/IF isolation of better than 30 and 17 dB, respectively, Finally, the entire front-end, including the LNA, image rejection filter, and mixer functions is realized on a 5.7-mm/sup 2/ GaAs substrate. The front-end has a conversion gain of 15 dB and an image rejection of more than 53 dB with 0-dBm LO power. The SSB noise figure is better than 6.4 dB, The total power dissipation of the front-end is 33 mW. The MMIC's are applicable as a single-block LNA and image-rejection filter, mixer, and single-block front-end in digital European cordless telecommunications. With minor modifications, the MMIC's can be applied in other wireless communication systems working around 2 GHz, e.g., GSM-1800 and GSM-1900.

We developed a 10-Gb/s AlGaInAs colorless remote amplified modulator with a gain peak detuned semiconductor optical amplifier using a selective epitaxy and semi-insulating buried heterostructure. The device provides up to 10-dB insertion gain and lossless operation together with static extinction ratio larger than 20 dB over a 50-nm range. Using this device, we achieved 10-Gb/s remote modulation over 80-nm spectral range in a back-to-back transmission. The device operates also in a single-mode fiber bidirectional link without penalty at 20 $^{\circ}$ C.

It is chiefly in schools for the deaf, kindergartens for the hard of hearing, and other facilities where hearing aids are fitted to children in Japan. Persons in charge of hearing aids in each school or facility, execute fitting to their own opinions, without a standard method of fitting. However, it is the general view that children should wear hearing aids regardless of hearing level and that they should learn to use their ears. In this paper, I described the fitting method in Japan. In addition, I explained in detail the fitting method that considers the functional gain which is becoming the main measurement, and introduce examples. I also explain that the effect of the hearing aid is measured by the functional gain, without the measure of insertion gain in Japan.

Previous work has shown that a normally aided ear tested without the hearing aid is better able to identify speech-in-noise than the unaided ear at high sound levels, while performance for the unaided ear is superior at lower sound levels [S. Gatehouse, J. Acoust. Soc. Am. 86, 2103-6 (1989); J. Acoust. Soc. Am. 92, 1258-68 (1992)]. This effect was further explored using intensity discrimination for complex stimuli. Stimuli were half-octave bandpass-filtered tone complexes centered at 0.25 and 3 kHz. Four bilateral, symmetric hearing-impaired listeners with mean HL of 24 dB at 0.25 kHz, and 58 dB at 3 kHz were tested. Intensity discrimination was performed across the dynamic range of the listeners. At sound-pressure levels greater than 85 dB, the normally aided ear tested without the aid was more sensitive to changes in intensity than the unaided ear, whereas at lower levels, the converse occurred. This pattern was observed only for the 3-kHz center frequency, and not for the 0.25-kHz center frequency. Insertion gain measurements using the aids at normal volume showed an average of 20 dB gain at 3 kHz, and -2 dB gain at 0.25 kHz. The changes in intensity discrimination in the normally aided ear are consistent with the frequency-gain characteristics of the hearing aid, and suggest that a change in intensity coding occurred.

This paper describes techniques for realizing microwave active filters using single transistor active resonators in a negative resistance configuration, The negative resistance topologies for both bipolar (AlGaAs/GaAs HBT) and FET (MESFET or HEMT) devices are studied and compared. The essence of the technique is that the input reactance of the transistor circuit resonates with an external capacitor or inductor, whilst the negative resistance is used to compensate for the losses in the resonator. It is shown that the FET device is ideally suited for this application as it can have a varactor-controlled negative resistance component. Three-stage and two-stage monolithic varactor-tuned bandpass filters have been demonstrated using this technique. The measured response of the three-stage filter exhibits a 120 MHz 3 dB-bandwidth centered on 2.3 GHz, 0 dB insertion loss with only /spl plusmn/0.1 dB ripple in the pass-band, up to 100 dB of stop-band attenuation at low frequencies, and over 50 dB of rejection up to 6 GHz. The two-stage filter exhibits a 400 MHz 3 dB-bandwidth centered on 4.7 GHz, with tunable insertion gain and only /spl plusmn/0.1 dB ripple in the pass-band.

Audiologists typically verify hearing instrument fitting using real-ear measurements (REM). Recently the modified pressure with stored equalization method (MPSE) has been recommended for use when verifying open non-occluding hearing instruments. The MPSE method does not use a reference microphone to maintain loudspeaker output during real-ear measurements and is therefore susceptible to changes in the signal level at the client's ear which result from movement of the client's head and torso during the verification process. To determine the size of these errors, the real-ear unaided response (REUR) was measured prior to and following the fitting of a non-functioning hearing aid in the contralateral ear. Twenty young adults participated. Identical head positions for the two measurements should yield zero difference measures across all frequencies measured. Loudspeaker-to-client azimuths of 0 degrees and 45 degrees were investigated. Mean difference measures across the frequencies investigated were less than 1 dB for both azimuths with one standard deviation from these mean differences typically less than 1.5 dB. Results suggest that the MPSE method does not introduce clinically significant errors in real-ear measurements when verifying hearing instrument fitting in the population examined.

In probe tube measures, the method used to equalize the sound field will determine the reference value used in calculating real ear insertion gain (REIG) and real ear aided gain (REAG). Several equalization methods are available with current probe tube systems. This study determined the effects of three equalization methods (substitution, modified comparison, and ipsilateral comparison) on REIG and REAG measures using open and closed earmolds for ear canals varying in circumference. Twelve subjects were selected representing a wide range of ear canal circumferences. Results revealed significant differences for REIG and REAG among the three equalization methods. These differences appear to be due to the different acoustic components included or excluded for each method. The results of this study suggest that the sound field equalization method used for probe tube measures needs to be considered when interpreting the hearing aid gain reported among various probe microphone units. Also, canal circumference may be a quick method for categorizing canal cavity size and appears to influence measured hearing aid gain.

Three hearing aid manufacturers provided custom full-shell in-the-ear hearing aids for each of 3 hearing-impaired subjects. Each manufacturer was instructed that the hearing aids should provide the maximum possible acoustic gain within the limits of hearing aid shell size and available components. Coupler gain, insertion gain, and functional gain were measured for each hearing aid. Gain measures were made with the volume control at either the full-on setting or the highest setting possible before the onset of acoustical feedback. Full-on coupler gain curves were similar across all nine hearing aids. Individual differences in concha/ear canal size and in the fit of the hearing aids produced substantial variance in insertion gain across hearing aids. Peak insertion gain varied from 41 to 58 dB. If 10 dB reserve gain is allowed, the range of estimated peak use gain from these maximum-gain in-the-ear hearing aids is 31–48 dB.

We report on an InAsP-InGaP electroabsorption modulator at 1.3 /spl mu/m integrated with a semiconductor amplifier. The fiber-to-fiber insertion gain reaches +10 dB. The 50-/spl mu/m-long modulator section exhibits a bandwidth of 36 GHz and a -17-dB extinction ratio with 3-V drive voltage. The integrated amplifier produced an RF-link efficiency of -26 dB at 20 GHz without any external amplification.

Objective: To study auditory acclimatization and outcome in first time hearing aid users fitted with state of the art hearing aids as a function of different hearing aid fitting protocols. Methods: Twenty-eight adult subjects participated in the study. Each subject was assigned to one of three study groups (named audiologist driven, AD; patient driven, PD; set-to-target, STT according to the fitting protocol used) and fitted with digital hearing aids (Bernafon Symbio). Speech recognition scores were measured in aided and unaided conditions over a 6-month period. Results: Five subjects (three from the PD-group, two from the STT group) decided to withdraw from the study during the 6-month-study period, leaving a total of 23 complete data sets for analysis. Aided speech understanding increased significantly over this time period in all three groups. However, average hearing aid insertion gain changes were small over the same period. There were no statistically significant differences in aided or unaided speech recognition scores between the three groups after 2 weeks or after 6 months. On average, twice as many fine tunings of the hearing aids were requested by the patients in the AD and the STT group than in the PD group and subjects in the AD and STT group used their hearing aids approximately twice as much as subjects in the PD group. Conclusions: The substantial increase in speech intelligibility without significant changes of the insertion gain of the hearing aids over a 6-month period in all three groups suggests a significant acclimatization effect. Although the speech recognition with hearing aids did not differ significantly among the three study groups after 6 months, the lower average wearing time and the higher number of withdrawals from the study in the PD group suggest that the patients’ needs are not adequately met. In terms of aided speech recognition scores and hearing aid wearing time the STT group and the AD group were very similar. However, comments of the patients and the higher rate of withdrawals in the STT group suggest an over-all advantage for the AD fitting protocol.

A new compact photonic-integrated modulator utilising a four-element reflective electro-absorption modulator-semiconductor optical amplifier (EAM-SOA) array and silica interferometric guide arrangement is presented. The EAM-SOA active layer consists of AlGaInAs quantum wells designed in selective area growth technology, which enables an insertion gain, and the mature silica platform provides reduced optical losses. As a result, error-free 50 Gbit/s RZ-QPSK signal generation is shown.