Donghyeon successfully defended his dissertation on “Effects of nonlinear algorithms on output signal-to-noise ratios of a digital hearing aid“, and he is on his way to his first tenure-track position! Well done, Donghyeon!
Akhila Tirupasur has received the Mary-Gates Undergraduate Research Scholarship for the Spring 2024 quarter! Congrats! Her project will systematically assess how individual listeners’ loudness growth vary with stimulus bandwidth. Results from the projects will be used to build auditory models that can capture individual listeners’ abilities to resolve spectral details.
Akhila Tirupasur receives Mary-Gates Undergraduate !Student Scholarship
This presentation was about exploring self-directed hearing aid fitting with two procedures: (1) preference-based adjustment of hearing aid’s amplification profile, (2) loudness-perception profiling.
Kursun, Bertan & Petersen, Erik & Shen, Yi. (2023). Exploring Self-directed Hearing-aid Fitting with No Booth And No Audiogram. 10.13140/RG.2.2.19575.19360.
Bertan Kursun, Erik Petersen, Yi Shen
Perceptual interactions between pitch and timbre have been demonstrated repeatedly using discrimination tasks of static sounds in psychoacoustics (Allen & Oxenham, 2014; Marozeau & de Cheveigne, 2007). Furthermore, interactions may be influenced by the congruency of pitch and timbre cues in the stimulus. Larger interference effects on F0 and SC discrimination have been observed when shifts in F0 and SC occurred in the same direction across intervals as opposed to inverse directions (Allen & Oxenham, 2014). Previous interference effects were often prompted via pitch and timbre cues that were static over the duration of the stimulus. Timbre and pitch, however, are rarely this simple in natural sounds. In the current study, effects of stimulus congruency on pitch-timbre interactions are investigated in static and dynamic sounds. Listeners discriminated the pitch of static complex sounds and sounds with movement in the fundamental frequency (F0) and spectral centroid (SC) in two yes/no tasks. Measures of pitch sensitivity indicate that stimulus congruency effects perceptual interactions to both static and dynamic stimuli, with larger effects as the difference between cues increase. Analyses on cue movement and congruency suggest larger relative interaction effects for dynamic sounds relative to static sounds.
Ryan Anderson, Yi Shen, William P Shofner
Sensitivity to the temporal properties of auditory patterns tends to be poorer in older listeners, and this has been hypothesized to be one factor contributing to their poorer speech understanding. This study examined sensitivity to speech rhythms in young and older normal-hearing subjects, using a task designed to measure the effect of speech rhythmic context on the detection of changes in the timing of word onsets in spoken sentences. A temporal-shift detection paradigm was used in which listeners were presented with an intact sentence followed by two versions of the sentence in which a portion of speech was replaced with a silent gap: one with correct gap timing (the same duration as the missing speech) and one with altered gap timing (shorter or longer than the duration of the missing speech), resulting in an early or late resumption of the sentence after the gap. The sentences were presented with either an intact rhythm or an altered rhythm preceding the silent gap. Listeners judged which sentence had the altered gap timing, and thresholds for the detection of deviations from the correct timing were calculated separately for shortened and lengthened gaps. Both young and older listeners demonstrated lower thresholds in the intact rhythm condition than in the altered rhythm conditions. However, shortened gaps led to lower thresholds than lengthened gaps for the young listeners, while older listeners were not sensitive to the direction of the change in timing. These results show that both young and older listeners rely on speech rhythms to generate temporal expectancies for upcoming speech events. However, the absence of lower thresholds for shortened gaps among the older listeners indicates a change in speech-timing expectancies with age. A further examination of individual differences within the older group revealed that those with better rhythm-discrimination abilities (from a separate study) tended to show the same heightened sensitivity to early events observed with the young listeners.
Dylan V. Pearson, Yi Shen, J. Devin Mcauley, Gary R. Kidd
Spectral weights in octave-frequency bands from 0.25 to 4 kHz were estimated for speech-in-noise recognition using two sentence materials (i.e., the IEEE and AzBio sentences). The masking noise was either unmodulated or sinusoidally amplitude-modulated at 8 Hz. The estimated spectral weights did not vary significantly across two test sessions and were similar for the two sentence materials. Amplitude-modulating the masker increased the weight at 2 kHz and decreased the weight at 0.25 kHz, which may support an upward shift in spectral weights for temporally fluctuating maskers.
Yi Shen, Lauren Langley
Auditory brain stem response (ABR) measurements provide a method to determine the hearing threshold of laboratory animals and humans who are unable to provide behavioral responses to auditory stimuli. Determining hearing threshold using ABR typically requires a large number of pre-selected frequency and stimulus levels, which may not be the most efficient method to sample the stimulus space. The goal of the current study is to develop an adaptive procedure that determines in situ the stimulus that will provide the best estimate of the threshold, based on data collected earlier in the procedure. A Gaussian Process model is iteratively fitted after each test level, and the subsequent test level is chosen at the interim threshold estimate predicted by the current model fit. Simulations of the adaptive procedure were conducted using previously collected toneburst ABR measurements from mice presented at 5 dB increments from 0 to 80 dB at seven frequencies ranging from 4 to 32 kHz. The thresholds determined by this procedure were compared to those produced by human raters who viewed the response at all stimulus levels. Initial results indicate that the threshold may be accurately estimated utilizing fewer stimuli levels than current methods, thereby reducing the duration of the measurements.
10.1121/10.0011243Petersen, Erik & Shen, Yi. (2023). Determining auditory brain stem response threshold using an adaptive stimulus selection procedure. The Journal of the Acoustical Society of America. 151.
Erik Petersen, Yi Shen
Purpose The signal-to-noise ratio (SNR) for speech presented in background noise may vary after being processed by digital hearing aids with nonlinear signal processing algorithms, such as wide dynamic range compression (WDRC). A phase inversion technique has been previously developed to assess the output SNR of hearing aids. However, systematic validations of this technique have not been conducted. This study aims to validate the phase inversion technique. Method A simulated hearing aid with multichannel WDRC was implemented, from which the output SNRs, computed via shadow filtering, for connected speech in background noise were directly computed. The agreement between the shadow filter output SNRs and those estimated using the phase inversion technique for the same stimuli was utilized to validate the phase inversion technique. The background noise was 2- or 20-talker babble noise, and the speech stimuli were presented at SNRs of −10 to +10 dB at the input of the simulated hearing aid. The simulated hearing aid was configured to provide amplification for four representative audiograms, and the WDRC was set to be fast or slow acting. To investigate the effects of additive noise, independent of the presented noise stimulus, on the phase inversion estimated output SNR, the same simulated hearing aid was implemented with an additive Gaussian noise at its input (45 and 60 dB SPL). Results Results showed that the phase inversion technique could either overestimate or underestimate output SNR, depending on the test condition; the estimation errors tended to coincide with temporal landmarks, such as natural pauses between consecutive sentences or fricatives; and increasing the simulated noise led to poorer estimates of output SNR. Conclusions Results imply that the accuracy of the phase inversion technique is dependent on the test conditions. Thus, the phase inversion technique should be used with caution, and its validity should be evaluated further.
Donghyeon Yun, Yi Shen, Jennifer J Lentz
Disclosed is a system and method for individualized hearing aid prescription which consists of a test procedure that enables the fitting of an individualized estimation of the SII model to individual listeners efficiently and an optimization process which translates the resulting individualized model to the prescribed gains across frequencies for programming into the user’s hearing aids. The test involves the recognition of one or more words presented in background noise, which better approximates the daily listening experiences of hearing-aid users compared to the pure-tone detection in a silent environment task which is commonly utilized during conventional audiometric testing. In the estimated SII model, five parameters describe in a custom fashion the relative weights of speech information across the five frequency bands for a given listener. The results from the speech test is used to determine the desirable amount of gain for each frequency region to optimize the user’s aided speech intelligibility. The resulting gains for the individual may then be programmatically applied to the individual’s prescribed hearing aid device(s).
Shen, Yi. (2023). SYSTEM AND METHOD FOR INDIVIDUALIZED HEARING AID PRESCRIPTION.
Yi Shen
The auditory brainstem response (ABR) can be used to estimate the hearing threshold of animals or human subjects who are unable to respond to behavioral measures. However, ABR can be time-intensive and is vulnerable to human subjectivity while interpreting the waveforms. An adaptive procedure has been developed to efficiently and objectively estimate ABR threshold. The procedure iteratively fits a Gaussian process (GP) model to the ABR waveforms collected so far and optimizes the subsequent stimulus. The algorithm was validated through numerical simulation using pre-collected human ABR at 0.5, 1.0, 2.0, and 4.0 kHz with levels from below threshold to 90 dB in 5 dB increments from a cohort of normal-hearing listeners. This led to a full stimulus space of approximately 55 stimuli per test ear. For each test ear, the ABR threshold was estimated by human raters based on the entire stimulus space. The ABR threshold was also estimated using the adaptive procedure, which iteratively sampled a subset (~35%) of the stimulus space. At the end of the adaptive procedure, the fitted GP model was able to capture the individual differences in waveform morphology between listeners. Furthermore, the threshold estimates from repeated runs of the adaptive procedure demonstrated adequate test-retest reliability.
Erik Petersen, Yi Shen