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We propose reconfiguration of the conventional feedback scheme to suppress the external-cavity time-delay signature (TDS) by adding noise phase modulation in the feedback of semiconductor laser. Noise-phase-modulated feedback introduces broad band noise frequencies into the feedback light and enables the suppression of the TDS. In this work, by means of simulations, the effect on TDS suppression of phase modulation (PM) index is explored. In addition, the influence of noise bandwidth variation is investigated. Using the auto-correlation function to quantity the TDS, we find that, for a large range of operating parameters, the TDS is significantly suppressed to the noise level and even submerged into the base noise. It is shown that suppression TDS is achievable over a wide operating parameter provided the noise generator bandwidth is of order 10 GHz and the PM index is greater than about 3. The proposed configuration will have widespread applications in contexts where suppression of the TDS is required.

We numerically examine the dynamics of individually dragged skyrmions interacting simultaneously with an array of other skyrmions and quenched disorder. For drives just above depinning, we observe a broadband noise signal with a 1/f characteristic, while at higher drives, narrowband or white noise appears. Even in the absence of quenched disorder, the threshold force that must be applied to translate the driven skyrmion is finite due to elastic interactions with other skyrmions. The depinning threshold increases as the strength of the quenched disorder is raised. Above the depinning force, the skyrmion moves faster in the presence of quenched disorder than in a disorder-free system since the pinning sites prevent other skyrmions from being dragged along with the driven skyrmion. For strong pinning, we find a stick-slip motion of the driven skyrmion which produces a telegraph noise signature. The depinning threshold increases monotonically with skyrmion density in the absence of quenched disorder, but when pinning is present, the depinning threshold changes nonmonotonically with skyrmion density, and there are reentrant pinned phases due to a competition between pinning induced by the quenched disorder and that produced by the elastic interactions of the skyrmion lattice.

BACKGROUND The study aims at investigating the effect of aging and noise exposure on the auditory system using auditory brainstem responses (ABRs), distortion product otoacoustic emissions (DPOAEs), and contralateral suppression of OAEs (CSOAEs). The objective was to compare DPOAEs, CSOAEs, and ABR in aged and noise-exposed individuals with the normal, to find an indicator for early diagnosis of auditory damage. METHODS Sixty adult male participants were divided into 3 groups. Group 1 included individuals not exposed to occupational noise and group 3 included individuals exposed to occupational noise who were

We build a computational rate model for a biological neural network found in mammals that is thought to be important in the localisation of the sound in the vertical plane. We find the response of neurons in the brain stem that participate in the localisation neural circuit to pure tones, broad band noise and notched noise and compare them to experimentally obtained response of these neurons. Our model is able to reproduce the sensitivity of these neurons in the brain stem to spectral properties of sounds that are important in localisation. This is the first rate based population model that elucidates all the response properties of the neurons in the vertical localisation pathway to our knowledge.

This paper describes a new mode detection method based on the compressive sensing approach, which has been developed in information technology to reduce samples required by the classical Nyquist–Sh...

Tinnitus treatments present a quandary for clinicians, but no thoroughly satisfactory medical treatments are offered to tinnitus patients.We compared sound therapy effects of the broad band noise (BBN) and the mixed pure tones on tinnitus patients with normal to mild hearing loss, and the possible mechanisms were discussed.This study was a double-blinded randomized controlled trial. The patients in two groups were followed up for three months. We used a BBN in group A, and mixed pure tones of nine different frequencies in group B. The Tinnitus Handicap Inventory (THI) and Visual Analog Scale (VAS) measuring were used to evaluate the handicap, loudness and anxiety of tinnitus.The THI, VAS scores of group B after 3 months were lower than those at baseline. The VAS scores of group B were lower than those of group A at 8 and 12 weeks.The mixed pure tones were more advantageous than BBN as the sound therapy for tinnitus patients with normal to mild hearing loss.This trial provides a special and effective sound therapy method. Tinnitus patients with normal to mild hearing loss will experience more positive effects.

As an objective and non-invasive method to evaluate functional state of medial olivo cochlear (MOC) system, there has been growing interest in contralateral suppression of distortion product otoacoustic emission (DPOAE). Also, MOC system can be quantified by measuring the difference DPOAE amplitude recorded in the presence of contralateral acoustic stimulation (CAS). The purpose of this study is to identify the optimal CAS level for measuring the DPOAE contralateral suppression. In order to do that, the effect of gender, direction of ear, and the CAS level of the DPOAE suppression for normal hearing adults were tested. Data were collected from the thirty six ears of the eighteen subjects with normal hearing in the both ears ranged from 21 to 26 years of age. DPOAE was tested by ILO 292 analyzer in DP-gram function. For each measurement, primary tones frequencies were ratio f2/f1 = 1.22(f1 < f2) and intensities were L1 = 65 dB SPL, L2 = 50 dB SPL. 2f1-f2 DPOAE was elicited using two pure tones and frequencies were measured in the range of 1,000 Hz to 6,727 Hz. Broad band noise was used for CAS of DPOAE. CAS was delivered through a TDH 39 headphone that was placed in the participant’s contralateral ear. CAS level was randomly presented at 50, 60, 65, 70, and 80 dB SPL. The results showed that, first, there was no significant effect of the direction of ear for DPOAE suppression (p > .05). The results showed that the DPOAE suppression was not significantly different between male and female (p > .05). However, the means and SDs of DPOAE suppression for 5 different CAS levels, 50, 60, 65, 70, and 80 dB SPL, were .66(±1.20), 1.02(±1.23), 1.47(±1.73), 1.58(±1.70), and 1.21(±1.46) dB. As the CAS levels increased, the majority of DPOAE suppression increased generally until 70 dB SPL. Taken together, the results of this study showed that CAS at different levels induced mainly DPOAE amplitude suppression. The amount of suppression increased as the CAS level was increased with the rolling phenomenon at 80 dB SPL than 70 dB SPL in CAS level. Consequently, the 70 dB SPL or more level appears to generate the acoustic reflex in normal ears, and the 70 dB SPL or less CAS level is expected to be efficient for observing decent DPOAE suppression.

The purpose of this study was to investigate Transient Evoked Otoacoustic Emissions (TEOAEs) with alternate stimulation for elderly group and suggest probability between tinnitus and efferent system. Twenty-eight subjects (56 ears) ranging from 65 to 86 years old were participated. The pure tone threshold average (0.5, 1, 2 kHz) of the right ear was 32.22±14.65 dB HL and the left was 28.83±11.64 dB HL. There were nineteen subjects without tinnitus and the others had various tinnitus. Four out of tinnitus group had spontaneous right unilateral type, two out of them had bilateral type, while the others had intermittent tinnitus in somewhere of head. Alternate stimulation for contralateral suppression of TEOAEs was broad band noise of 70 dB SPL. Contralateral suppressions of TEOAEs were recorded in almost all subjects used every frequency (1, 1.4, 2, 2.8, 4 kHz), and TEOAEs suppressions were shown significantly on left ears of all subjects (t = -2.06, p = .049). TEOAEs of female were lower than male's in almost frequencies except 4 kHz, but TEOAEs differences of suppression were not appeared significantly between male and female (p > .05). Alternate TEOAEs suppressions were investigated in all frequencies without tinnitus group and varied in each frequency with tinnitus group. These results were achieved using a small pool of subjects but exposed a possibility for clinical application of TEOAEs associated with the efferent system.

The auditory cortex (AC) of the rat has been the subject of many studies, yet the details of its functional organization are still not well understood. We describe here the functional organization of the AC in young rats (strain Long Evans, aged 30–35 days, anesthetized with ketamine/xylazine) on the basis of the neuronal responses to acoustic stimuli. Based on the neuronal responses to broad band noise (BBN) and pure tone bursts, the AC may be divided into the primary auditory cortex (AI) and three other core fields: anterior (AAF), suprarhinal (SRAF) and posterior (PAF) as well as an unspecific region (UR) inserted between the AI and AAF. The core fields are surrounded by a belt area. Neurons in the AI, AAF, SRAF and PAF showed well defined characteristic frequencies (CF) in response to pure tone stimulation; in contrast, UR neurons responded only at high intensities without a clear CF. Neurons responding only to BBN stimulation were found mostly in the belt area. The putative borders between the core fields were determined by changes in their tonotopic gradient; however, no tonotopic organization was found in the PAF. Neurons with the shortest response latencies to BBN stimulation were found in layer 4 (L4) and layer 6 (L6) in the AI, while those with the longest latencies in the superficial layers (L1/2) of the belt area. Similar principles of responsiveness were observed when the spike rate in response to BBN stimulation was evaluated, with the highest rate present in L4 of the AI and the lowest in L1/2 of the belt area. According to the shape of the peristimulus time histograms, the responses of neurons in the AC of the rat may be classified as pure onset, sustained, onset-sustained, double peak or late onset. The most dominant in all fields, as well as in all layers, was the pure onset response. Our findings offer further cues for understanding the functional organization of the AC in the rat.

The purpose of this study was to investigate distortion product otoacoustic emission (DPOAE) measurements before and after contralateral suppression at frequency fine structure. 8pts/octave DP-gram was measured at f2 frequencies ranging from 841 Hz to 8,000 Hz in fifty six ears of normal hearing adults with and without contralateral broad band noise (BBN) at 70 dB SPL. The data were analyzed depending on groups by gender, age(20's, 30's, and 40's+) and directions of the ear. Results showed the followings: (1) DPOAE amplitude was decreased significantly with presence of broad band noise, showing contralateral suppression. (2) At the frequency fine structure, change in DPOAE amplitude before and after suppression was significant. The great amplitude change was observed between 1,000 and 2,000 Hz for most participants. (3) Change in DPOAE amplitude before and after suppression was not significant depending on gender and age, but was significant depending on directions of the ear. (4) Change in DPOAE amplitude before and after suppression was significant for peak and dip frequencies. Also, change in DPOAE amplitude was mostly suppressed at the peak frequencies, however, change in DPOAE amplitude was varied at the dip frequencies. A larger inter-subject variability was observed in the dip frequencies. The results suggest that measuring DPOAE contralateral suppression at peak frequencies in DPOAE would improve efficiency of the auditory efferent system assessment.

Transient evoked otoacoustic emission (TEOAE) is being a non-invasive, objective technique and required less time to get administered can be easily used to find out effect of short duration broad band noise (BBN). However one must know the sensitivity of TEOAEs in predicting susceptibility of noise induced hearing loss. Thus the present study has taken up to find out the effect on TEOAE amplitude because of short duration exposure of BBN. Results indicated that there was statistically significant reduction in amplitude of TEOAE at all frequencies except 1 kHz (p

The experiments described here used event-related potentials (ERPs) to investigate the neural processes of the horizontal effect, in which visual performance is worst for horizontal and best for oblique orientations. EEGs were recorded while human adult subjects performed an orientation identification task with broad-band noise stimuli. The results showed that the difference between cardinal orientations and oblique orientations first occurred at P2 component around 200ms post-stimulus onset, which is much later than the traditional oblique effect. Additionally, the P3 was much smaller and earlier for oblique orientations than for cardinal orientations. These findings indicated that, compared to the classical oblique effect, the horizontal effect with broad-band noise stimuli might occur at relatively later stages of visual information processing and might involve more complex neural mechanisms.

Sound reverberation is an important problem in some industrial environments. As indicated by the Occupational Safety and Health Act of 1970, noise is responsible for the psychological and physiological ills of workers. Therefore reduction of reverberation becomes essential. For maintenance and other reasons, the thickness of sound absorbers used for reverberation control may be constrained. Consequently there is interest in minimizing noise using sound absorbers with constrained thickness. Optimization of a composite absorber using a simulated annealing algorithm is presented. Simulated annealing is a stochastic relaxation technique based on analogy with the physical process of annealing metal. The algorithm requires a mathematical model for the acoustical properties of the absorber. Before optimization, the accuracy of the mathematical model was checked against experimental data. A program for optimizing in respect of broad band noise at a specified receiver has been created and run. Results prove that SA optimization provides a quick and efficient approach in designing constrained thickness composite sound absorbers.

The utility of R. Keith’s (1977) method of screening for hearing sensitivity using the contralateral acoustic-reflex threshold (ART) for broad-band noise (BBN) was tested in persons with cerebral palsy (CP). Three groups of participants were included in this prospective study. The first group comprised 20 normal-hearing individuals without CP whose results were used as normative data. The second group comprised 16 participants with normal hearing and CP. The third group comprised 22 participants with sensorineural hearing loss and CP. The results of this study indicate that Keith’s screening method employing ART for BBN can be used successfully in a population with multiple handicaps where a quick, inexpensive, readily available, and accurate method is needed.

Amaç: Bu çalışmanın amacı duyusal modülasyon bozukluğuna yol açan migren hastalığı olan kişilerde işitme sistemi reşeksi ölçümünde kullanılan bir test olan kontralateral otoakustik süpresyon testinin sonuçlarının değerlendirilmesidir.Yöntem: Çalışmaya nöroloji polikliniğine başvuran, Uluslararası Başağrısı Derneği’nin 2004 yılı kriterlerine göre migren tanısı alan ve vestibüler şikayeti olmayan gönüllü migren hastaları ve sağlıklı gönüllüler dahil edildi. Bütün gönüllülere tam otolojik muayene, saf ses odyometri testi yapıldı. Bilateral otoakustik emisyon yanıtı alınan 30 gönüllü migren hastası ve karşılaştırma için yaş ve cinsiyet özellikleri gönüllü hasta grubuna benzeyen 30 sağlıklı gönüllü çalışmaya dahil edildi. Çalışmaya dahil edilen gönüllülere kontralateral 50 dB SPL geniş bant gürültü ile maske yapılarak 65 dB click uyaran ile maskeli ve maskesiz otoakustik emisyon ölçümleri yapıldı. Her iki gruptan elde edilen veriler karşılaştırıldı.Bulgular: Sağlıklı gönüllülerin değerlendirilen 60 kulağının 40’ında (%67) süpresyon testi pozitif olarak tespit edilirken migren hastalarının değerlendirilen 60 kulağından 30’unda (%50) süpresyon testi pozitif olarak tespit edildi. Fakat süpresyon pozitişiği oranlarında ve süpresyon emisyon değerlerinde istatistiksel olarak anlamlı bir fark izlenmedi. İki grup arasında istatistiksel olarak anlamlı bir fark olmasa da migrenli grupta kontralateral supresyon cevaplarında azalma izlendi.Sonuç: Vestibüler şikayeti olmayan migren hastalarında normal kişilerle karşılaştırıldığında istatistiksel olarak anlamlı olmasa da kontralateral süpresyon cevaplarında bir azalma izlenmektedir. Daha büyük seri içeren yeni çalışmalar ile kontralateral otoakustik emisyon testi vestibüler şikayeti olmayan migren hastalarında odyovestibüler şikayetlerin erken tanısında kullanabileceği kanaatindeyiz.Anahtar sözcükler: Kontralateral süpresyon testi, MOC reşeksi, non-vestibüler migren, otoakustik emisyon., Objective: Our aim was to investigate contralateral suppression ofotoacoustic emission for the evaluation of auditory reflex in patientswith migraine which is a disease that may cause dysfunction of sensorial modulation.Methods: Voluntary migraine patients without vestibular symptomswho consulted to Neurology Clinic, and diagnosed according to theIHS 2004 criteria, and healthy volunteers were included in the study.All volunteers underwent complete otorhinolaryngologic and puretone audiometric examinations. Thirty voluntary migraine patients withbilateral otoacoustic emission measurements, and 30 healthy volunteersmatched in terms of age and sex were included in the study. Otoacousticemission measurements were obtained with 65 dB SPL click stimuluswith and without mask by masking with contralateral 50 dB SPL broadband noise. Responses were compared between two groups.Results: Positive result was obtained in suppression tests in 40 of 60(67%) ears of healthy volunteers and in 30 of 60 (50%) ears ofmigraine patients. However, there was no statistically significant difference between groups regarding positive suppression frequency andsuppression values. Even though a statistically significant differencebetween migraine patients without vestibular involvement and control group was not seen, there was a decrease in contralateral suppression responses in the migraine group.Conclusion: Although it is statistically insignificant, we have demonstrated that migraine patients without vestibular symptoms showed a decreasein the suppression values compared to the healthy volunteers. We believethat in new studies with larger series, contralateral otoacoustic emissionsuppression test can be used as an early tool to diagnose audiovestibularsymptoms in migraine patients without any vestibular involvement.

The study compares permutation-based and coarse-grained entropy approaches for the assessment of complexity of short heart period (HP) variability recordings. Shannon permutation entropy (SPE) and conditional permutation entropy (CPE) are computed as examples of permutation-based entropies, while the k-nearest neighbor conditional entropy (KNNCE) is calculated as an example of coarse-grained conditional entropy. SPE, CPE and KNNCE were applied to ad-hoc simulated autoregressive processes corrupted by increasing amounts of broad band noise and to real HP variability series recorded after complete vagal blockade obtained via administration of a high dose of atropine (AT) in nine healthy volunteers and during orthostatic challenge induced by 90° head-up tilt (T90) in 15 healthy individuals. Over the simulated series the performances of SPE and CPE degraded more rapidly with the amplitude of the superimposed broad band noise than those of KNNCE. Over real data KNNCE identified the expected decrease of the HP variability complexity both after AT and during T90. Conversely SPE and CPE detected the decrease of HP variability complexity solely during T90 as a likely result of the more favorable signal-to-noise ratio during T90 than after AT. Results derived from both simulations and real data indicated that permutation-based entropies had a larger susceptibility to broad band noise than KNNCE. We recommend caution in applying permutation-based entropies in presence of short HP variability series characterized by a low signal-to-noise ratio.

In order to test the frequency specificity of the efferent suppressive effect on otoacoustic emissions, changes in the 2f1-f2 distortion product otoacoustic emission (DPOAE) levels induced by contralateral stimuli of different spectra were measured in 10 normally hearing adults. Three types of contralateral stimuli were used: (i) a set of 6 pairs of pure tones with the same frequencies as used for DPOAE stimulation; (ii) 6 narrow-band noise signals with cut-off frequencies equal to the frequencies of the primary tones used for DPOAE stimulation; and (iii) broad-band noise with a bandwidth of 840-6,000 Hz. A small suppressive effect was observed mainly in the mid-frequency region. Broad-band noise was more effective at suppressing DPOAEs than narrow-band noises and two-tone complexes. Occasionally, small enhancements in DPOAE amplitudes were observed. Based on the results of this study, it is concluded that DPOAE changes induced by contralateral stimuli are not frequency-specific, and are too small to have routine clinical value.

High performance control valves may be subjected to noise problems especially when gas is the operating fluid. Depending on some geometric characteristics, the noise production can be characterized by broad band noise or tonal noise. When the latter condition occurs, the generated noise could overcome the limit of acceptance and the device does not respect the standard of usability. In a previous work, a dependency between the tonal noise and the main geometrical characteristics of a control rotary valve has been settled by experimental tests. Starting from these fluid dynamic observations in this work we coupled the modal analysis of the structure with experimental data to deeply understand this phenomenon. The natural frequencies of different perforated plates placed in a circular duct (configuration which mimics the full open control valve condition) are therefore considered to verify which of them are responsible of the tonal noise, generated by the interaction between the flow field and the acoustic one, observed in the experimental tests. To do this, the frequency modes consistent with the tonal noise generation, are numerically investigated by changing the geometrical characteristic of the device. By considering the rotary valve fully open, we especially investigated the effects of the plate thickness, the hole diameter and distribution.

We are very grateful to the author(s) of this letter for taking the time to read and respond to our article [1]. With all our respect, we reviewed their thoughtful letter which raised the important issue concerning the optimal stimulus for sound therapy implemented in tinnitus retraining therapy (TRT). The major issue that they wanted to point out was that the broadband noise TRT (bTRT) group had more severe tinnitus (Tinnitus Handicap Inventory [THI]=54.22±22.41) compared to mixed noise TRT (mTRT) (THI=42.5±22.27) and narrowband noise TRT (nTRT) (THI=48.25±25.56) group. And since patients with more severe tinnitus tend to show higher improvements compared to those with milder form of tinnitus [2], it seems possible that the superior performance of bTRT could also be contributed by the tinnitus severity factor. Their recommendation was to perform a future study with subjects who have almost equal baseline tinnitus severity scores or to perform an analysis of covariance (ANCOVA) with the baseline tinnitus severity (e.g., THI score) as the covariate. We agree with the shortcoming of our article that the authors have pointed out. The tendency of better outcome in the more severe tinnitus groups has also been found in previously published article regarding the prognostic factors of TRT [3]. Although we tried to control all confounding factors, a few variables which might influence the outcomes were basically not manageable, because of the retrospective design of our study. Accordingly, in this correspondence article we have reanalyzed our data and tried to advocate that broad band noise therapy may be preferable in TRT, even after controlling the pretreatment severity of tinnitus induced distress.

This paper deals with aerodynamic sounds generated by the curved columns in a uniform air flow experimentally. The curved column is formed in V-shape by bending a straight column to an angle of 2θ. The angle θ means the angle between the direction of air flow and a one-sided straight part of V-shaped column. The bend part has a radius of curvature of R. In the experiment, the effects of θ's and R's on the aerodynamic sound have been examined in detail. The results of the frequency analyses of aerodynamic sounds show that when θ≤90°, eminent aeolian tones are generated by the curved columns and moreover, that the peak frequencies of aeolian tones are affected by the values of R and θ. However, when θ > 90°aeolian tones are not generated but whistling noises generated in a broad frequency range.

We have experimentally studied the relationship between the periodic velocity fluctuation in the near wake of a rotating NACA 65 Blade and the generated broad band noise at different setting angles of the blade. The typical periodic velocity fluctuation in the near wake was not clearly observed at a design point but was observed at the attack angle at off design points. The frequency of the produced velocity fluctuation caused by Karman vortex shedding from the trailing edge of the blade increased toward the tip of the blade. Then, the spectrum of noise generated from the blade becomes broad band. In addition, we have proposed a method to predict the spectrum of noisc generated from blades due to Karman vortex shedding. The validity of the method was experimentally verified.

Three groups of 24 subjects were exposed to a 1000–Hz tone or broad band noise in a sound chamber. During the exposures subjects were engaged in an easy reaction time test or a difficult grammatical reasoning test. For each exposure and work subjects adjusted the noise to a tolerance level defined by its interference with task performance. During the simple reaction-time task significantly higher sound-pressure levels were accepted than during the reasoning test. At the tonal exposure, much lower levels were accepted than during the exposure to broad-band noise. For continuous sound exposures much higher levels were accepted than for noncontinuous exposures. For tonal exposures the difference was approximately 5 dB, for the broad-band exposures approximately 9 dB. In a separate study the effects of the noncontinuity of the noise and pauses were analysed. The raised annoying effect of the noncontinuous noise was not more affected by the noncontinuity of the noise periods than by the noncontinuity of the pauses. The results imply that the annoying reactions to the sound will be increased for repetitive noise and that the reaction is highly influenced by the over-all noncontinuity of the exposure.

We discuss the effects of both temporal and quenched noise in underdamped Josephson junction series arrays that are globally coupled through a resistive load and driven by an rf current. We study the breakdown of the law of large numbers in the turbulent phase of the Josephson arrays. This corresponds to a saturation of the broad band noise S0 for a large number N of junctions. We find that this phenomenon is stable against temporal noise (thermal fluctuations) and quenched noise (disorder). The behavior of S0 versus temperature T, for large N, shows three different regimes. For 0 Tc2, S0 is mainly due to thermal fluctuations, since it increases linearly with T.

International audience; In this paper we will discuss an optimization loop used during the fan blade design phase to get a compromise for the efficiency of the fan and broad band interaction noise at different design points. Indeed the aerodynamicians design constraints differ from the acousticians’ ones. To minimize the fuel consumption the fan must be designed for a best efficiency in cruise, but to reach the environmental requirements, the fan blades have to be quiet (and so efficient) during takeoff and landing. In this work, results obtained with an optimization tool will be discussed. The space parameter is defined with design blades parameters such as angle at leading edge, camber, chord, thickness... A special attention will be paid to the efficiency of the fan at high RPM and the interaction broad band noise at off-design points.

The photoluminescence of excitons confined in an electric field tunable coupled AlAs/GaAs quantum well has been investigated at $T\ensuremath{\ge}350$ mK and magnetic fields $H\ensuremath{\le}14$ T. In the indirect regime where electrons and holes are separated both in real and in $k$ space, the magnetic field was found to result in (i) a strong change of both the photoluminescence intensity and decay time which is attributed to anomalies in the exciton transport and (ii) an appearance of a huge broad band noise in the photoluminescence intensity which is evidence for exciton condensation.

A series of experiments was conducted concerning the effect of amplitude-modulated (AM) sounds on the impression of broad-band noise. The following results were found:(1) AM sounds in broad-band noise were detected when S/N was around zero (S: the level of AM sound, N: 1/3 octave band level of broad-band noise with center frequency corresponding to the carrier frequency of AM sounds). Close examination showed that carrier frequency, modulation frequency and modulation depth had a systematic effect on the detection of AM sounds.(2) The loudness of broad-band noise mixed with AM sounds could be approximately evaluated by loudness level based on ISO 532B (LLz).(3) The timbre of broad-band noise mixed with AM sounds was judged to be more metallic as the carrier frequency of AM sounds became higher and to be more clamorous as the carrier frequency became lower. This suggests that the timbre is deteriorated when AM sounds are mixed with broad-band noise. The three factors were extracted by the factor analysis: they were “metallic” or “unpleasant, ” “powerful” and “rough.”

The aim of this study was to investigate the functional development of cochlear active mechanisms and of the medial efferent olivocochlear system. Otoacoustic emissions (evoked and spontaneous) were recorded in 42 preterm neonates (conceptional age ranging form 33 to 39 weeks) and a control group of 20 young normal-hearing adults. Medial olivocochlear system activity was examined by coupling evoked otoacoustic emission recording to a contralateral stimulation. Otoacoustic emission recordings were carried out using the Otodynamic ILO88 software and hardware. The stimuli were unfiltered clicks and the contralateral stimulation was broad band noise of 50 and 70 dBSPL delivered by an Adam generator. The results revealed the presence of EOAEs and SOAEs from at least 33 weeks in humans, suggesting that the functional maturation of the outer hair cells is nearly complete at that age. The study further revealed that the contralateral stimulation had no effect on evoked otoacoustic emissions in preterm neonates. The lack of activity observed in medial olivocochlear system indicated functional immaturity here, at least before full-term birth.

In the present study we examined the relationship of the loudness discomfort level LDL of different signals. We carried out measurements in 97 patients, all of whom suffered from a sensorineural hearing loss. The results showed almost no difference between the LDL of pure tones and narrow band noise. The LDL of broad band noise showed a good correlation to the LDL of 250 Hz. Only the LDL of monosyllables ranged at a higher SPL. For an up-to-date hearing aid fitting, all forms of LDL should be taken into consideration. This is especially necessary when using digital hearing aids.

A series of experiments was conducted concerning the loudness and timbre of broad bandnoise mixed with frequency-modulated sounds. The results suggested the follow ings:(1) FM sounds overlapped on broad-band noise can be just detectable when S/N is around zero (S: the level of FM sound, N: the 1/3 octave band level of broad-band noise with center frequency corresponding to carrier frequency of FM sound).(2) FM sounds overlapped on broad-band noise can be detected at S/N of-10 dB or less when it is interrupted.(3) The loudness of broad-band noise shows good correspondence with Leq. However, when a prominent frequency component, such as FM sounds, is included, loudness level based on ISO 532B (LLz) shows better correspondence than Leq.(4) The timbre becomes deteriorated when the level of specific frequency component in creasesor when its frequency becomes high. These effects were found even when the overall values of Leq were kept constant. Neither Leq nor LLz is sufficient for evaluating these effects. The method for calculating sharpness proposed by von Bismarck is an ap propriatemethod for evaluating the metallic aspect of the timbre.

AIM To assess the effects of occluding the round window on the degree of hearing loss following exposure to broad band noise. DESIGN Following opening of the middle ear bulla in both ears of ten sand rats, auditory nerve-brainstem evoked response (ABR) thresholds were determined in each ear separately using an insert earphone. The round window of one ear was then occluded with super-glue. The opposite ear was sham-operated. ABR thresholds were again assessed immediately. The animals were then exposed to 113 dB SPL broad band noise for 12 hours. 24 hours after the round window was occluded, which was 8-10 hours after the end of the noise exposure, ABR thresholds were again determined in each ear. In four control animals, the round window was blocked, but they were not exposed to noise. RESULTS Following the noise exposure, the mean ABR threshold elevation in the round window blocked ears (54.5 +/- 5.5 dB) was significantly (p < 0.004) greater than that in the sham-operated ear (40.5 +/- 8.6 dB). In the four control ears, there was no change in ABR threshold 24 hours after the round window was occluded. CONCLUSION Occluding the round window was not accompanied by a threshold elevation, but following noise exposure, the noise induced hearing loss was increased, probably by reducing the efficacy of an inherent protective mechanical mechanism.

We have investigated the phase slip process which occurs between regions with different time-averaged charge density wave velocities. Longitudinal phase slip at electrical contacts is temperature activated and requires a minimum voltage V ps o . We evaluate the characteristic parameters and their dependence on the CDW order parameter Δ(T). Transverse phase slip, or velocity shear, occurs as a finite size effect associated with irregular crystal cross sections, and is the dominant source of broad band noise in NbSe 3 .

A short range broad band noise radar system using an electrically tunable true-time-delay line in silicon is presented. The delay line has to cover the interested scanning range (here 2.3 m) and show low dispersion. The delay line consists of discrete switchable lines realized in hybrid form and a on chip continual tunable coplanar delay line. The noise radar operates at the X-band (10.7 GHz-12 GHz). Measurements are presented with a fixed obstacle in the scanned range.

An animal model of chronic renal failure (CRF) was created by the 5/6 nephrectomy procedure in guinea pigs. Levels of serum Cr and BUN were abnormally elevated at 1,2 and 3 months after the procedure. ECoG (CAP, CM) was recorded through a silver ball electrode placed on the round window 1,2 and 3 months after surgery. EP was measured with a glass microelectrode from the scala media via the round window membrane. Only slight ECoG changes were seen 1 month after surgery. On the other hand, moderate or profound changes were observed 2 and 3 months after-surgery. No significant decrease in EP was found in the post-surgery animals which distinctly showed abnormal CAP, CM, although a limited number of animals were studied. The above results indicate that CRF is one of the etiological factors of cochlear dysfunction and the sensory hair cells appeared to be the site of the lesion. To study the interaction between noise exposure and CRF, 1 month post-surgery animals with only a little change in ECoG were exposed to a broad band noise. Changes in the ECoGs were followed up for 6 hours after the noise exposure. In contrast to the controls, animals with CRF did not recover from the reduced ECoG which occurred immediately after the noise exposure. This suggests synergistic interaction between noise and CRF.

This study compares the contralateral suppressive effect of the auditory efferent system on cochlear microphonics versus distortion‐product OAEs (DPOAEs) in order to identify the potential versus the mechanical changes of the outer hair cells. This was achieved by recording the CM and DPOAEs from the right ear of 16 normal‐hearing young female adults with and without broad band noise (BBN) in the left ears. DPOAEs were recorded at 0.5, 2, and 4 kHz F2 frequencies, and at 0.5 and 2 kHz tone bursts and clicks for CM using condensation and rarefaction polarity. Results revealed that both DPOAEs and CM recordings showed suppression and enhancement effects of BBN, but there were no statistically significant differences within each recording (with‐without BBN) and between recordings (CM versus DPOAEs) (P = 0.923 at 0.5 kHz, P = 0.858 at 2 kHz, and P = 0.332 at 4 kHz or clicks). This could be related to the small effect and the lack of sensitive enough equipment. In general, larger effect was observed at 0.5 kHz in DPOAEs, but at 2 kHz in CM. Interestingly, when the stimulus polarity of the CM was changed from condensation to rarefaction at 2 kHz in the presence of BBN, six participants showed CM recordings that changed from suppression to enhancement or vice versa, suggesting a possible relationship.

Determinations of interocclusal tactile threshold levels so far have involved neither appropriate psychophysical approaches nor an assessment of the mechanical and thermal properties of the foils used. Twenty subjects (12 females) aged 18 to 50 (mean age 35) were tested for their absolute threshold level (RL). Both the method of limits and the staircase method were applied to determine the active or passive RL. For the active RL assessment, foils of different thicknesses were placed between edge-to-edge opposed incisors during gentle biting. Inner ear receptors of the blindfolded subjects were blocked by broad band noise applied through earphones, because vibrations induced by occlusal contact and conducted through bone might be perceived by these receptors. The foils presented were aluminum (Al), tin (Sn), polyester (PE) and calibrated steel (St) (thickness ranging from 8 to 50 μm) which offer different physical and thermal properties. The range of RL of the group varied between 8 μm for aluminum to 46 μm for polyester for 50% correct assessments. Increasing the foil temperature from room temperature (20°C) to body temperature (35°C) significantly increased the RL for conducting materials (one-way blocked ANOVA). These results indicate that temperature exchange takes place while presenting conducting foils at 20°C (cold stimulus) interocclusally, which influences the RL by activating thermosensitive receptors. The passive RL determination with classical von Frey-hairs resulted in a mean axial RL of 3.0 g. Both psychophysical RL assessments (method of limits, staircase method) gave reproducible and similar results as ascertained by ANOVA. Furthermore, a positive correlation was established between active and passive RL (Pearson correlation test). It is concluded that the physical and thermal properties of the foils need careful consideration in future experiments on threshold determination. Although active RL determination may involve the activation of non-periodontal receptors, it remains a realistic parameter to monitor tactile function of teeth.

One way of attenuating broad band noise that propagates through ducts or pipe systems is to use one or more reactive-type acoustic components, each of which is specifically designed for optimal performance at a particular frequency range. This paper uses the transfer matrix method for predicting the transmission loss (TL) of a system with resonators connected to the main duct and a side branch duct modified with a zero-mean-flow expansion chamber. The method is applied to different configurations, and the numerical predictions are compared with the results obtained using finite element methods. Our results indicate that broadband resonators and a side branch duct with an expansion chamber, fitted as a countermeasure for broadband noise, can offer significant benefits