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The microwave auditory effect has been widely recognized as one of the most interesting and significant biological phenomena from microwave exposure. The hearing of pulsed microwaves is a unique exception to the airborne or bone-conducted sound energy, normally encountered in human auditory perception. This chapter describes the research studies leading to scientific documentation that absorption of a single microwave pulse impinging on the head may be perceived as an acoustic zip, click, or knocking sound, depending on the incident microwave power. A train of microwave pulses to the head may be sensed as an audible buzz, chirp, or tone by humans. It discusses the neurophysiological, psychophysical, and behavioral observations from laboratory studies involving humans and animals as subjects. The objective is to present what is scientifically known about the microwave auditory effect.

Disregarding onset and offset effects, interaurally delaying a 500 Hz tone by 1.5 ms is identical to advancing it by 0.5 ms. When presented over headphones, humans indeed perceive such a tone lateralized toward the side of the nominal lag. Any stimulus other than a tone has more than one frequency component and is thus unambiguous. It has been shown that phase ambiguity can be resolved when increasing the stimulus bandwidth. This has mostly been attributed to the integration of information across frequencies. Additionally, interaural timing information conveyed in the stimulus envelope within a single frequency channel is a second possible cue that could help to resolve phase ambiguity. This study employs stimuli designed to differ in the amount of envelope fluctuation while retaining the same power spectral density as well as interaural differences. Any difference in lateralization must thus be a result of the difference in envelope. The results show that stimuli with strong envelope fluctuation require significantly smaller bandwidths to resolve phase ambiguity when compared to stimuli with weak envelope fluctuation. This suggests that within-channel information is an important cue used to resolve phase ambiguity.

In various embodiments, methods, systems, and vehicles are provided for masking a tonal noise of a motor. In certain embodiments, a vehicle includes a drive system and an active masking acoustic signal generator (AMAG). The drive system includes a motor generating a tonal noise. The AMAG is configured to at least facilitate masking the tonal noise, by introducing a complementary harmonic tone, injecting dithering into the motor, or both.

The perplexing acoustical properties of a landscape architecture feature of Academy Park on the Purdue University campus have long been the subject of speculation. The feature, known informally as the “Clapping Circle,” consists of sixty-six concentric rings of stone tiles. When someone claps while at the middle of the circle, they hear a high-pitched squeak immediately afterwards. Experiments were conducted by the Purdue student chapter of the Acoustical Society of America to characterize this effect. The response to a clap played from an omnidirectional speaker placed at the center of the circle was recorded using a microphone positioned above the loudspeaker. Spectrograms of the recorded responses revealed the squeak to consist of a descending tone and its harmonics. This tone disappeared from the spectrogram when the tiles were covered with absorbing blankets. A model based on scattering from the bevels between the tile rings reproduced the descending frequency of the squeak. Similarly to famous stepped structures with notable acoustics, the tiles were found to scatter sound best when the wavelength was not larger than the tiles' spatial period. Thus, it was concluded that the squeak is an example of an acoustical diffraction grating which creates a repetition pitch caused by scattering from the tile formation. © 2021 Institute of Noise Control Engineering.

Blowing a recorder at a low to moderate blowing speed with the toneholes all closed yields the lowest note in the range of the instrument. As the blowing speed is increased, the tone abruptly changes to the tone an octave higher. This "jump" in the frequency of the dominant spectral component of the tone is referred to as "regime change." Interestingly, in conversations with recorder players, several have mentioned that regime change seems to occur at a significantly lower blowing speed for bass recorders than for instruments that sound an octave or more higher. In this paper we study regime change in the recorder and use Navier-Stokes modeling to confirm and study differences in the behavior of different instruments in the recorder family. We show, using modeling, how the regime change threshold in a model of the bass recorder can be increased by changing the geometry in the vicinity of the labium. These results are then confirmed through experimental studies of real recorders with designs inspired by the modeling results. The insights gained from these results suggest new recorder designs that may produce instruments that in some respects are more playable than current instruments.

A two-dimensional model of the edge tone is studied by a highly accurate and reliable method of direct numerical simulation of the compressible Navier-Stokes equations, and used to verify key features observed in previous experimental and numerical studies, and to discover new features related to the jet motion and the edge tone generation mechanism. The first and second modes of the edge tone that are numerically reproduced agree well with Brown’s equation. In the mode transition region, dynamical mode transition is observed at a fixed jet velocity. For both first and second modes, the pressure distributions are antisymmetric with respect to the edge plate, and the sound intensity is proportional to the fifth power of the jet velocity. These results are consistent with the edge tone being radiated from a dipole-like source. Spatial profiles of the velocity and the velocity variance of the oscillating jet are also investigated for each mode over a range of the jet velocity including the mode transition regime. The amplitude of the velocity oscillation becomes constant with increasing jet velocity, while a measure of the amplitude of the velocity variance profile, which is introduced to characterize the strength of the jet fluctuation and named the ’fluctuation strength’, is proportional to the third power of the jet velocity. Some properties of the fluctuation strength correspond to properties of the sound intensity, including the first mode having larger amplitude than the second mode, and the way of deviating from the power law at smaller values of jet velocity and in the mode transition region. It is proposed that the third-power law exhibited by behavior of the fluctuation strength could be related to the increase of the skewness observed in the velocity profile with increase of jet velocity, and a model calculation is used to support this proposal.

A method for improving the dynamic range of frequency-modulated continuous-wave (FMCW) radar systems is presented. Bright echo signals detected with FMCW radars can carry strong phase noise sidelobes, especially for radars at W-band and higher frequencies where extremely quiet local oscillators do not exist or are not practical. These sidelobes can hide targets that would otherwise be detectable by the radar. Owing to the mathematical symmetry of phase noise with respect to a dominant carrier tone, the phase noise on the negative-frequency side of a bright echo can be used in post-processing to coherently cancel the corresponding phase noise on the positive-frequency side, revealing the presence of any weak target on the positive-frequency side. We show experimentally how this procedure improves the dynamic range of an airborne 167 GHz cloud radar by up to 18 dB, albeit with a detection sensitivity penalty of about 3 dB.

A novel over-the-air (OTA) beamforming calibration procedure is proposed, which can be applied to different types of multiple-input multiple-output (MIMO) transmitting antennas. The method consists of using two tones on each antenna element, the main tone, and the tickle tone. The latter one operates in a different frequency for each antenna element and is used to obtain the optimum phase that needs to be set for each element to generate a beam in the desired direction, at the main tone frequency. The novel method was applied to linear, planar, 3-D antennas, and noncollocated multiantennas to validate its applicability to different antenna types. Line-of-Sight (LOS) and non-LOS experimental results demonstrate that the method can be used to retrieve the required phase to fully control the antenna radiation pattern. An optimum radiation pattern and lowest error vector magnitude (EVM) can be achieved even under high multipath effects/non-LOS conditions. A comparison between the performance and the application of the array factor (AF) theory is presented for practical indoor scenarios, demonstrating the effectiveness of the method. It is demonstrated that the method may be an alternative to the calibration of nonstandard MIMO antennas, where the AF computation is complex or not possible.

The dentofacial system is closely related to the musculoskeletal, digestive, nervous, cardiovascular systems, etc. The functioning of the dentofacial system affects nutrition, breathing, swallowing, speech, hearing, etc., where occlusion is one of its main parameters. Many pathologies in the dentofacial system are also associated with a change in the efforts of the masticatory muscles, where hypertonicity of the superficial masticatory muscle is most common. The article considers an example of her hypertonicity by biomechanical modelling. For this, the problem of determining of the masticatory muscle efforts was solved at the maximum value of the force of compression of the jaws, which was 600 N. The cases were considered when the minimum possible value of the force of the superficial masticatory muscle was 70%, 80% and 90% of the maximum value. It was found that for the case while the minimum values of the efforts of all masticatory muscles do not exceed 50% of their maximum possible values, then the distribution of muscle efforts remains unchanged, i.e. the values of muscle efforts do not change. When at least one of the muscles exceeds its half of the maximum possible effort, it is observed that the efforts of the remaining muscles on the same side of the face decrease or remain approximately at the same level, and on the opposite side, the muscle efforts initially decrease, and at 80% and 90% of the maximum possible magnitude of the effort of the superficial chewing muscle increases again. In further works, various combinations of hypertonicity of the masticatory muscles, as well as the hypotonia of these muscles, are assumed.

1964년부터 국악기의 현대화, 표준화, 과학화 등을 위해 국악기에 대한 연구와 개량사업이 추진되었으나, 국악기가 가지고 있는 고질적인 문제들은 큰 성과를 거두지 못하였다. 이러한 주요 원인중 하나는 국악기에 대한 악기 음향학 연구가 선행되지 못한 것으로 분석되고 있다. 국악기 중 협주곡이나 독주곡에서 사용하고 있는 소금은 맑은 음색과 높은 음역으로 인하여 국악관현악단에서도 서양 오케스트라에서의 플룻의 역할을 수행하고 있는 악기이다. 본 논문에서는 비슷한 음색으로 들리는 소금과 플룻의 음색을 악기가 가지고 있는 배음의 분포와 구조를 통해 분석하였다. 이를 통해 전체적인 음색은 소금에 비하여 플룻이 풍부하고 부드럽다는 것을 알 수 있었고, 고음으로 갈수록 배음들의 비슷한 구성으로 인하여 두 악기의 음색이 비슷하게 들린다는 것을 알 수 있었다. 추후에는 다양한 국악기들에 대한 악기음향학적 연구가 지속적으로 수행되어 국악기의 대중화와 세계화에 작게나마 도움이 되길 기대한다.

We studied the cognitive processes involved in pure acoustic memory retrieval using ERPs and independent component analysis (ICA) of the ERPs. We used a modified Sternberg task with pure tones as memory items, with 3 memory set size conditions (2, 4, or 6 tones), and a control condition in which no task-relevant tone was presented (tones replaced by white-noise segments). Participants reported the presence or absence of a probe tone in the memory set. EEG signals were recorded using a BioSemi ActiveTwo system, with 64 active electrodes following the 10–10 system and average-mastoids reference. A P3 component, at electrode POz, was elicited by the probe when items were to be held in memory, no P3 was observed in control trials. With an increase in memory load, P3 amplitude decreased, accuracy was lower, and response time (RT) longer. There was a clear recency effect, in the electrophysiological and behavioral results reflected in a larger P3, shorter RT, and higher accuracy, when the probe matched the last tone of a sequence than when it matched any of the other presented tones, regardless of memory load. P3 amplitude and behavioral results were similar across all the other serial positions and loads. The results suggest that acoustic memory for pure tones is mediated by two subsystems: one encoding the last item with high probability, and another for all other serial positions. ICA of the ERPs isolated parieto-occipital ICA components with larger activations for probes that matched the last serial position than for earlier ones, and an anterior component that had little activation for the last serial positions and large activations for all earlier ones, corroborating the two-systems theory.

This paper investigates the acoustic correlates of word initial prominence and tone in Chácobo, a southern Pano language of the northern Bolivian Amazon. This paper reports the results of a production study with five speakers producing trisyllabic words with a word final high tone. It tests a claim found in the literature that there is an additional word-initial prominence in such forms and determines its acoustic correlates compared with high tone. This study used trisyllabic forms in morphophonological contexts where these forms would appear with a final high tone. In such forms, high tone and word-initial prominence do not overlap (e.g., "panaß̞í" "asaí"). The paper takes into account five acoustic correlates across the three syllables of these words: F1, F2, F0, duration, intensity. The paper finds that the initial syllable in these words shows a statistically significant increase in intensity. There is significant speaker variation with respect to whether duration is a correlation of initial stress and the results do not provide clear evidence that initial stress is marked with duration. The final high-tone marked syllables are distinguished based on an increase in F0 and secondarily with vowel duration. Whether pitch is also a correlate of stress requires future research. The paper interprets these results as suggesting that Chácobo is a language in which tone and stress co-exist. The study thus provides instrumental evidence for a phenomenon suggested to occur in some Pano languages. The limitations of this study, including the fact the results have more than one interpretation in light of current discussions concerning stress and tone, are also discussed.

The objective of this research is to assess aerodynamic noise sources and the wind velocity conversion of the similarity law in an increasing wind velocity. We measured the aerodynamic noise that radiates from cylinders with and without periodic holes and a pantograph model with and without a sound insulating plate in a low-noise high-speed wind tunnel. The noise level of the cylinders was in proportion to the sixth power of wind velocity because the cylinders acted as a dipole sound source. The effect of noise reduction caused by the change in flow structure, that is, the periodic holes, also continued. However, the second peak noise radiating from the cylinder was in proportion to the sum of the sixth power and the eighth power of wind velocity and was underestimated by wind velocity conversion based on a dipole sound source. The noise level of the pantograph model with the sound insulating plate was in proportion to lower than the sixth power of wind velocity in contrast to the pantograph model itself. This is because the noise reduction effect of the sound insulating plate had a frequency characteristic. In this research, when increasing the wind velocity, the dominant pantograph noise frequency region shifted to a higher level, and the dominant noise level began to be affected by the noise reduction of the sound insulating plate. This caused the reduction effect of the sound insulating plate to be underestimated by 2.5 dB due to the noise level conversion of wind velocity. To solve this problem, the plate’s theoretical reduced noise level, which was calculated by using the Fresnel number, was subtracted from the estimated noise level of the pantograph itself. This lead to pantograph noise with the sound insulating plate being estimated within a 0.8-dB difference.

The paper deals with the possibility of direction finding and determining the coordinates of a source of acoustic signal emitted by a surface or underwater vehicle in the subsonic frequency range. For this purpose combined hydroacoustic receivers are used. During the first experiment, the estimates of the systematic component of direction finding error were obtained when the source emitted a tone or polyharmonic signal, and the direction finding results were averaged over a set of frequencies. The obtained results were used in the second experiment for estimating the error in determining the coordinates of the polyharmonic signal emitter consisting of three combined receivers (CR) which form the navigation base distributed in the horizontal plane.

Hypothesis This study tests the hypothesis that it is possible to find tone or noise vocoders that sound similar and result in similar speech perception scores to a cochlear implant (CI). This would validate the use of such vocoders as acoustic models of CIs. We further hypothesize that those valid acoustic models will require a personalized amount of frequency mismatch between input filters and output tones or noise bands. Background Noise or tone vocoders have been used as acoustic models of CIs in hundreds of publications but have never been convincingly validated. Methods Acoustic models were evaluated by single-sided deaf CI users who compared what they heard with the CI in one ear to what they heard with the acoustic model in the other ear. We evaluated frequency-matched models (both all-channel and 6-channel models, both tone and noise vocoders) as well as self-selected models that included an individualized level of frequency mismatch. Results Self-selected acoustic models resulted in similar levels of speech perception and similar perceptual quality as the CI. These models also matched the CI in terms of perceived intelligibility, harshness, and pleasantness. Conclusion Valid acoustic models of CIs exist, but they are different from the models most widely used in the literature. Individual amounts of frequency mismatch may be required to optimize the validity of the model. This may be related to the basalward frequency mismatch experienced by postlingually deaf patients after cochlear implantation.

In this study, 4 methods of detecting sinusoid targets in white Gaussian noise are investigated. Averaging FFTs coherently and non-coherently is examined. A brute force method is introduced and investigated. Using a single large FFT spanning the observation window is also considered. Detection performance is studied on targets whose frequencies drift over time. It is determined that averaging non-coherent FFTs is a safe choice in a detection system. The preferred size of the FFT used for tone detection as well as the number of spectra to average is driven by the nature of the target tone frequency drift. This information is especially useful when high sample rate detectors are used to find tones from low quality transmitters because making FFTs too large or taking too many averages may hinder detection.

In this study, 3 methods of tone detection are investigated, the non-coherent averaging method, the power spectral method, and the cross-power spectral method. The target tones are simulated with frequency drift. Analysis is performed to find optimal FFT sizes and number of spectra to average. P D vs. P FA curves are then created and used to compare these methods. This analysis is particularly useful when using high sampling rate detectors to find tones produced with lower quality oscillators that experience frequency drift since using FFTs that are too large or averaging too many spectra may actually decrease detectability.

We perform an electromagnetic particle simulation of triggered emissions in a uniform magnetic field for understanding of nonlinear wave-particle interaction in the vicinity of the magnetic equator. A finite length of a whistler-mode triggering wave packet with a constant frequency is injected by oscillating an external current at the equator. We find that the first subpacket of rising-tone triggered emissions is generated after termination of the injection of the triggering wave in the homogeneous magnetic field. By analyzing resonant currents and resonant electron dynamics in the simulation, we find that the formation of an electron hole in a velocity phase space forms resonant currents, and the currents cause wave amplification and frequency increase. As the very initial stage of the generation process, phase-bunching occurs at the wavefront of the triggering wave. The phase-bunching is caused by the rotation of electrons in the velocity phase space because of the gradient of the distribution function in the parallel velocity. The phase-bunched untrapped electrons are scattered to the loss cone giving energy to the electromagnetic waves, while the electrons in the low density region are trapped by the wave potential, forming an electron hole. The time scale of the initial formation process of the electron hole is related to the duration time of the triggering wave necessary for generation of triggered emissions. The duration time is determined by the interaction time. For the generation of triggered emissions, the interaction time is more than 1/4 of the nonlinear trapping period in the present simulation.

The presented work investigates the tone noise of three booster stages designed for a high bypass ratio turbofan. Calculations were performed at the approach operational conditions. The frequency domain numerical method of multistage turbomachines tone noise simulation, developed in CIAM (Central Institute of Aviation Motors) and implemented in 3DAS (3 Dimensional Acoustics Solver) in-house solver was used. The aim was to perform once again the validation of the computational method and to obtain better understanding of the mechanisms of tone noise generation in multistage turbomachines. The results of the investigation were compared with the experimental data obtained in the CIAM C-3A acoustic test facility. In general satisfactory correspondence between the numerical calculations and the experiment was observed. This can be treated as a significant argument for the validity of the frequency domain method of the multistage turbomachinery tone noise calculations.

In the present work a numerical study of tone noise generated by the last stage of the Low Pressure Turbine (LPT) of an aircraft engine designed for a medium-haul civilian aircraft has been conducted. The impact of struts on the tone noise characteristics is estimated. The method for turbine noise calculation is based on numerical integration of the three-dimensional unsteady Reynolds averaged Navier-Stokes equations using an in-house code for multi-stage simulations. To obtain the tonal characteristics of the generated noise, the pressure pulsation field is processed using the methods of radial mode analysis. The calculated pressure fluctuations contain all possible components of the frequency-modal spectrum, which allows us to determine profile of the generated tone noise and find propagating modes with maximum amplitude. The calculations showed that the presence of struts leads to a scattering effect, which manifests as an increase in the number of generated circumferential modes. These circumferential modes propagate both downstream and upstream and increase the total level of tone noise. The amplitudes of circumferential modes related to two different types of the interaction, rotor-stator and rotor-struts, are compared.

It is difficult to localize the source of a tone in a room because standing waves lead to complicated interaural differences that become uninterpretable localization cues. This paper tests the conjecture that localization improves if the listener can move to explore the complicated sound field over space and time. Listener head and torso movements were free and uninstructed. Experiments at low and high frequencies with eight human listeners in a relatively dry room indicated some modest improvement when listeners were allowed to move, especially at high frequencies. The experiments sought to understand listener dynamic localization strategies in detail. Head position and orientation were tracked electronically, and ear-canal signals were recorded throughout the 9 s of each moving localization trial. The availability of complete physical information enabled the testing of two model strategies: (1) relative null strategy, using instantaneous zeros of the listener-related source angle; and (2) inferred source strategy, using a continuum of apparent source locations implied by the listener's instantaneous forward direction and listener-related source angle. The predicted sources were given weights determined by the listener motion. Both models were statistically successful in coping with a great variety of listener motions and temporally evolving cues.

Objective Examine the effect of language experience on auditory evoked and oscillatory brain responses to lexical tone in passive (ACC) and active (P300) listening conditions. Design Language experience was evaluated using two groups, Mandarin- vs. English-listeners (with vs. without lexical tone experience). Two Mandarin lexical tones with pitch movement (T2 rising; T3 dipping) produced on the syllable /ba/ were used as stimuli. For passive listening, each tone was presented in a block. For active listening, each tone was the standard (80%) or deviant (20%) presented in two blocks. Presentation order was counterbalanced across participants in both tasks. Study sample 10 adult Mandarin-listeners and 13 Australian-English-listeners contributed to the data. Results Both global field power (GFP) and time frequency analysis (TFA) failed to detect group differences in passive listening conditions for the ACC response. In contrast, the active listening condition revealed significant group differences for T2. GFP showed a trending significance with larger GFP (less consistent responses) in English- than Mandarin-listeners. TFA showed significantly higher alpha synchronisation (more focussed attention) for Mandarin- compared to English-listeners. Conclusions Acoustic responses to speech is influenced by language experience but only during active listening, suggesting that focussed attention is linked to higher level language processes.

In a sequence of otherwise equal sounds, listeners tend to hear a series of trochees (groups of two sounds with an initial beat) when every other sound is louder; they tend to hear a series of iambs (groups of two sounds with a final beat) when every other sound is longer. The article presents evidence that this so-called "Iambic-Trochaic Law" (ITL) is a consequence of the way listeners parse the signal along two orthogonal dimensions, grouping (Which tone is first/last?) and prominence (Which tone is prominent?). A production experiment shows that in speech, intensity and duration correlate when encoding prominence, but anticorrelate when encoding grouping. A model of the production data shows that the ITL emerges from the cue distribution based on a listener's predicted decisions about prominence and grouping respectively. This, and further predictions derived from the model, are then tested in speech and tone perception. The perception results provide evidence that intensity and duration are excellent cues for grouping and prominence, but poor cues for the distinction between iamb and trochee per se. Overall, the findings illustrate how the ITL derives from the way listeners recover two orthogonal perceptual dimensions, grouping and prominence, from a single acoustic stream. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Yorùbá dùndún drumming is an oral tradition which allows for manipulation of gliding pitch contours in ways that correspond to the differentiation of the Yorùbá linguistic tone levels. This feature enables the drum to be employed as both a musical instrument and a speech surrogate. In this study, we examined four modes of the dùndún talking drum, compared them to vocal singing and talking in the Yorùbá language, and analyzed the extent of microstructural overlap between these categories, making this study one of the first to examine the vocal surrogacy of the drum in song. We compared the fundamental frequency, timing pattern, and intensity contour of syllables from the same sample phrase recorded in the various communicative forms and we correlated each vocalization style with each of the corresponding drumming modes. We analyzed 30 spoken and sung verbal utterances and their corresponding drum and song excerpts collected from three native Yorùbá speakers and three professional dùndún drummers in Nigeria. The findings confirm that the dùndún can very accurately mimic microstructural acoustic temporal, fundamental frequency, and intensity characteristics of Yorùbá vocalization when doing so directly, and that this acoustic match systematically decreases for the drumming modes in which more musical context is specified. Our findings acoustically verify the distinction between four drumming mode categories and confirm their acoustical match to corresponding verbal modes. Understanding how musical and speech aspects interconnect in the dùndún talking drum clarifies acoustical properties that overlap between vocal utterances (speech and song) and corresponding imitations on the drum and verifies the potential functionality of speech surrogacy communications systems.

Jet screech is an intense pure tone which has attracted decades of research interest due to its possible detrimental effect on engineering structures. Its modes and closure mechanisms have been investigated analytically, experimentally, and numerically; however, there are still outstanding questions regarding the generation and propagation of instabilities in the near-field region. Recent studies have identified that these instabilities travel inside the jet potential during the screech process to form the complete feedback loop. Using dynamic mode decomposition on a three-dimensional pressure near field from large-eddy simulation results, the present study examines the viability of modal decomposition to provide further insights into the screech mode and its associated characteristics, and investigates the effect of temperature mixing in jet screech. The results show that modal decomposition identifies the helical structure of screech mode. Furthermore, a method is proposed to reveal the temporal evolution of dynamic screech mode. It was found that the bulk behavior of the pressure field at screech frequency propagates backward toward the nozzle exit. Ministry of Education (MOE) The authors gratefully acknowledge the support provided for this study by the Singapore Ministry of Education AcRF Tier-2 Grant (Grant No. MOE2014-T2-1-002).

© 2019 Elsevier Ltd This paper proposes a hybrid packet loss concealment (PLC) algorithm for the MDCT-based audio codec with different PLC strategies on tone dominant source signals and noise like signals respectively. It is meaningful to find that the phase angle of the MDCT-MDST coefficients decreases linearly with the increase of the frame index but the amplitude keeps unchanged for the stationary source signal with dominant tonal components. Therefore an efficient frame interpolation method is designed to accurately estimate the phase angle and the magnitude of the MDCT-MDST coefficients of the lost frame. For the noise-like signals without overwhelming tonal components, a modified shaped-noise insertion is proposed to improve the audio perception. Both objective and subjective test results show that the proposed algorithm provides better performance than the existing ones for both music and voiced speech signals.

Objectives to characterize differences in wideband power reflectance for ears with and without cochlear implants (CIs), to describe electrically evoked stapedial reflex (eSR)-induced changes in reflectance, and to evaluate the benefit of a broadband probe for reflex threshold determination for CI recipients. It was hypothesized that reflectance patterns in ears with CIs would be consistent with increased middle ear stiffness and that reflex thresholds measured with a broadband probe would be lower compared with thresholds obtained with a single-frequency probe. Design Eleven CI recipients participated in both wideband reflectance and eSR testing. Ipsilateral reflexes were measured with three probes: a broadband chirp (swept from 200 to 8000 Hz), a 226 Hz tone, and a 678 Hz tone. Wideband reflectance measures acquired from 28 adults without CIs and with normal middle ear function served as a normative data set for comparison. Results Considering the group data, average reflectance was significantly greater for ears with CIs across 250 to 891 Hz and 4238 to 4490 Hz compared with the normative data set, although individual reflectance curves were variable. Some CI recipients also had low 226 Hz admittance, which contributed to the group finding, considering the control group had clinically normal 226 Hz admittance by design. Electrically evoked stapedial reflexes were measurable in nine of 14 ears (64.3%) and in 24 of 46 electrodes (52.5%) tested. Reflex-induced changes in reflectance patterns were unique to the participant/ear, but similar across activators (electrodes) within a given ear. In addition, reflectance values at or above 1000 Hz were affected most by activating the stapedial reflex, even in ears with clinically normal 226 Hz admittance. This is a higher-frequency range than has been reported for acoustically evoked reflex-induced reflectance changes and is consistent with increased middle ear stiffness at rest. Electrically evoked reflexes could be measured more often with the 678 Hz or the broadband probe compared with the 226 Hz probe tone. Although reflex thresholds were lower with the broadband probe compared with the 678 Hz probe in 16 of 24 conditions, this was not a statistically significant finding (Wilcoxon signed-rank test; p = 0.072). Conclusions The applications of wideband acoustic immittance measurements (reflectance and reflexes) should also be considered for ears with CIs. Further work is needed to describe changes across time in ears with CIs to more fully understand the reflectance pattern indicating increased middle ear stiffness and to optimize measuring eSRs with a broadband probe.

The phenomenon of the singing wineglass is familiar to many. Most people have run a finger along the rim of a wine glass with the right speed and pressure to get it to whistle a tone or perhaps heard a glass harmonica being played. However, have you ever noticed and wondered why the vibrations caused by a finger on a glass produce a pulsating sound, rather than a steady, constant-amplitude vibration? Further exploration reveals that the sound and pulsations of a wine glass vary depending on the way the wine glass is stimulated. In this paper, we investigate and model the characteristic sounds produced by three different cases: the pulsating sound exhibited by a finger run along the rim of a wine glass, the steady tone produced by a stationary finger on a rotating wine glass, and the decaying pulsations exhibited by a struck rotating wine glass. Analyzing the qualitative differences among these three cases provides opportunities for students to hone experimental, modeling, and data analysis skills in an intermediate level undergraduate experimental physics course.

Sensorineural hearing loss is associated with elevated hearing thresholds, reduced dynamic range, and loudness recruitment. Signal processing with dynamic range compression is used in hearing aids for presenting all the sounds comfortably within the limited dynamic range of the listener. A dynamic range compression technique, named as ‘sliding-band compression’, is proposed to overcome the shortcomings of the commonly used single-band and multiband compression techniques. The gain at each frequency index is calculated as a function of the short-time power in an auditory critical band centered at it. The technique avoids the attenuation of high-frequency components due to the presence of strong low-frequency components, which may occur in single-band compression. Further, it avoids distortions in the shape of spectral resonances and discontinuities during the resonance transitions, which may occur in multiband compression. The proposed technique was implemented for offline processing and compared with single-band compression and multiband compression using objective measures and different test inputs. For two-tone inputs, the single-band compression showed attenuation of the high-frequency tone with an increase in the level of the low-frequency tone. For swept-frequency single-tone input, the multiband compression showed errors in the tone amplitude of 1.5–2.5 dB for compression ratio of 2–10. Sliding-band compression did not show either type of error. The technique has been also implemented using a fixed-point processor for real-time processing with audio latency acceptable for face-to-face communication.

Acoustic coordinated reset (CR) therapy based on neuromodulation and neuroplasticity principles has been proposed for the treatment of tonal tinnitus. The original therapy involved periodic delivery of randomly ordered sequences of four low-level tones centered around the frequency of a tone that matched the tinnitus pitch, fT, with fixed ratios relative to fT and delivered several hours/day over several weeks. Here we transform the original CR tone selection method to a more perceptually-relevant equivalent rectangular bandwidth (ERB) frequency scale, the ERBN-number scale. Specifically, we provide a mathematical model that enables calculation of CR tones that accounts for fT- and hearing loss-related ERB widening and ERB overlaps and gaps of CR tone alignments. Further, the model ensures symmetric CR tone alignments based on modelling studies that indicate the effect is optimal if the CR stimuli are symmetrically spaced relative to the tinnitus-related population of abnormally synchronized cortical neurons to activate the adjacent sub-populations. We also present experimentally testable ERB-based CR tone alignment strategies and explain how to use the ERB-based model in experiments, clinical studies, other types of tinnitus sound treatment such as tailor-made notch music training and limitations of our approach.

Theoretical and numerical models of chorus waves are reviewed in this paper. Specifically, we focus on the nonlinear wave particle interactions and the current understanding of the frequency chirping of rising tone chorus waves. Various other related topics, such as the optimal excitation condition of chorus, the formation of subpackets, and the non-adiabaticity of the nonlinear interaction are also discussed. We end this review paper with a short list of questions of chorus waves that are still under research and debate.

In natural listening contexts, especially in music, it is common to hear three or more simultaneous pitches, but few empirical or theoretical studies have addressed how this is achieved. Place and pattern-recognition theories of pitch require at least some harmonics to be spectrally resolved for pitch to be extracted, but it is unclear how often such conditions exist when multiple complex tones are presented together. In three behavioral experiments, mixtures of three concurrent complexes were filtered into a single bandpass spectral region, and the relationship between the fundamental frequencies and spectral region was varied in order to manipulate the extent to which harmonics were resolved either before or after mixing. In experiment 1, listeners discriminated major from minor triads (a difference of 1 semitone in one note of the triad). In experiments 2 and 3, listeners compared the pitch of a probe tone with that of a subsequent target, embedded within two other tones. All three experiments demonstrated above-chance performance, even in conditions where the combinations of harmonic components were unlikely to be resolved after mixing, suggesting that fully resolved harmonics may not be necessary to extract the pitch from multiple simultaneous complexes.

The source of audible tones occurring with a coaxial nozzle is explored experimentally as well as computationally. The hardware is comprised of an inner and an outer nozzle, without a center-body, that are held together by a set of four struts. With increasing jet Mach number ( Mj), first a tone occurred at about 2550 Hz around Mj = 0.06. At higher Mj, a tone at 5200 Hz dominated the noise spectra. The corresponding non-dimensional frequency, based on the effective thickness of the inner nozzle lip and jet exit velocity, turned out to be about 0.2, a value characteristic of Karman vortex shedding. Thus, vortex shedding from the inner nozzle lip could be linked to the tones. From a comparison of acoustic wavelengths and nozzle dimensions, as well as locations of the pressure nodes and anti-nodes from the computational results, it was inferred that the vortex shedding excited one-quarter-wave resonances within the divergent sections of the nozzle. Such resonances in the inner and the outer nozzles produced the higher and the lower frequency tones, respectively.