Binaural Detection Thresholds Research Articles

Binaural detection thresholds and audio quality of speech and music signals in complex acoustic environments.

Every-day acoustical environments are often complex, typically comprising one attended target sound in the presence of interfering sounds (e.g., disturbing conversations) and reverberation. Here we assessed binaural detection thresholds and (supra-threshold) binaural audio quality ratings of four distortions types: spectral ripples, non-linear saturation, intensity and spatial modifications applied to speech, guitar, and noise targets in such complex acoustic environments (CAEs). The target and (up to) two masker sounds were either co-located as if contained in a common audio stream, or were spatially separated as if originating from different sound sources. The amount of reverberation was systematically varied. Masker and reverberation had a significant effect on the distortion-detection thresholds of speech signals. Quality ratings were affected by reverberation, whereas the effect of maskers depended on the distortion. The results suggest that detection thresholds and quality ratings for distorted speech in anechoic conditions are also valid for rooms with mild reverberation, but not for moderate reverberation. Furthermore, for spectral ripples, a significant relationship between the listeners' individual detection thresholds and quality ratings was found. The current results provide baseline data for detection thresholds and audio quality ratings of different distortions of a target sound in CAEs, supporting the future development of binaural auditory models.

Monaural and binaural phase sensitivity in school-age children with early-childhood otitis media

Objective Previous research has linked recurrent otitis media (OM) during early childhood to reduced binaural masking level differences (BMLDs) in school-age children. How this finding relates to monaural processing abilities and the individual otologic history has not been investigated systematically. The current study, therefore, addressed these issues. Design Sensitivity to monaural and binaural phase information was assessed using a common test paradigm. To evaluate the influence of the otologic history, overall OM duration, OM onset age, and the time since the last OM episode were considered in the analyses. Study sample Children aged 6–13 years with a history of recurrent OM (N = 42) or without any previous ear diseases (N = 20). Results Compared to the controls, the OM children showed smaller BMLDs (p < 0.05) whereas their monaural and binaural detection thresholds were comparable (p > 0.05). After controlling for age, the otologic history factors failed to predict the BMLDs of the OM children. Their monaural detection thresholds were correlated with the binaural detection thresholds (r = ∼0.5, p < 0.05) but not the BMLDs. Conclusions The current study suggests that early-childhood OM can impair binaural processing abilities in school-age children.

No more than “slight” hearing loss and degradations in binaural processing

Listeners having, at most, "slight" hearing loss may exhibit substantial deficits in binaural detection [Bernstein and Trahiotis. (2016). J. Acoust. Soc. Am. 140, 3540-3548; (2018). J. Acoust. Soc. Am. 144, 292-307]. This study assessed whether such listeners also exhibit deficits discriminating interaural temporal disparities (ITDs) or interaural intensitive disparities (IIDs) and whether any deficits observed in those discrimination tasks would be accounted for by the interaural cross-correlation based model that successfully accounts for binaural detection. Thresholds were measured for detection of tones masked by noise in the NoSπ configuration and discrimination of ITD or IID. Gaussian noises (100 Hz-wide), served as maskers in the detection task and as reference and target stimuli in the discrimination tasks. Stimuli were centered at 500 Hz or 4 kHz. The latter were transpositions of stimuli centered at 125 Hz. Results demonstrate that listeners having, at most, slight hearing loss and who exhibit deficits in binaural detection, also exhibit deficits in ITD- and IID-discrimination. Coupled with appropriate decision variables, the cross-correlation-based model that accounts for elevated binaural detection thresholds among such listeners also accounted for their elevated ITD- and IID-thresholds. The deficits in all three tasks appear to stem from increased levels of stimulus-dependent, additive internal noise.

Effects of interaural delay, center frequency, and no more than ”slight” hearing loss on binaural processing: Behavioral data and quantitative analyses

Recent neurophysiological studies concerning “hidden hearing loss” have motivated investigators to attempt to uncover behaviorally-measured auditory deficits that might exist in human listeners who would be categorized via standard audiometry as having normal hearing or, at most, “slight” hearing loss. We hypothesized that behavioral measures of binaural auditory performance could reveal the presence of deficits that may not be discoverable via standard audiometric testing or via measures of monaural processing. That hypothesis was based on the notion that monaural (perhaps, peripheral) deficits would be effectively multiplied via binaural interaction. Groups of listeners, all having no greater than “slight” hearing loss were tested. Binaural detection thresholds were elevated across a wide range of center frequencies for listeners whose absolute thresholds at 4 kHz exceed 7.5 dB HL. Quantitative predictions made via an interaural correlation-based model of binaural processing suggest that the elevated binaural detection thresholds observed for listeners having slightly elevated absolute thresholds stem solely from their having elevated levels of internal noise. They appear to stem neither from reduced sensitivity to signal-dependent changes in information derived from the stimuli as processed internally nor from increased noise along the listener’s putative internal delay line.

Effects of interaural delay, center frequency, and no more than "slight" hearing loss on precision of binaural processing: Empirical data and quantitative modeling.

This study assessed how precision of binaural processing is affected by center frequency (CF), interaural temporal disparity (ITD), and listeners' hearing status. Tonal signals and 100-Hz-wide Gaussian noise maskers were employed at CFs ranging between 250 and 8000 Hz, in octave steps. In addition, for CFs of 2000, 4000, and 8000 Hz, transposed maskers and signals were employed. All listeners had no greater than "slight" hearing losses (i.e., no thresholds greater than 25 dB HL). Across all CFs and ITDs tested, binaural detection thresholds were elevated for listeners whose absolute thresholds at 4 kHz exceeded 7.5 dB HL. That outcome is consistent with results from Bernstein and Trahiotis [(2016). J. Acoust. Soc. Am. 140, 3540-3548]. Quantitative predictions of binaural detection thresholds derived via a comprehensive interaural correlation-based model of binaural processing were highly accurate across the entire set of data. The modeling results suggest that elevated thresholds from listeners having small hearing losses stem from elevated levels of stimulus-dependent, additive internal noise. They do not appear to stem from increased levels of noise within the central binaural comparator or from reduced sensitivity to changes in interaural correlation produced by the addition of the signal to the masker.

Characterizing the binaural contribution to speech-in-noise reception in elderly hearing-impaired listeners

To scrutinize the binaural contribution to speech-in-noise reception, four groups of elderly participants with or without audiometric asymmetry <2 kHz and with or without near-normal binaural intelligibility level difference (BILD) completed tests of monaural and binaural phase sensitivity as well as cognitive function. Groups did not differ in age, overall degree of hearing loss, or cognitive function. Analyses revealed an influence of BILD status but not audiometric asymmetry on monaural phase sensitivity, strong correlations between monaural and binaural detection thresholds, and monaural and binaural but not cognitive BILD contributions. Furthermore, the N0Sπ threshold at 500 Hz predicted BILD performance effectively.

Behavioral manifestations of audiometrically-defined "slight" or "hidden" hearing loss revealed by measures of binaural detection.

This study assessed whether audiometrically-defined "slight" or "hidden" hearing losses might be associated with degradations in binaural processing as measured in binaural detection experiments employing interaurally delayed signals and maskers. Thirty-one listeners participated, all having no greater than slight hearing losses (i.e., no thresholds greater than 25 dB HL). Across the 31 listeners and consistent with the findings of Bernstein and Trahiotis [(2015). J. Acoust. Soc. Am. 138, EL474-EL479] binaural detection thresholds at 500 Hz and 4 kHz increased with increasing magnitude of interaural delay, suggesting a loss of precision of coding with magnitude of interaural delay. Binaural detection thresholds were consistently found to be elevated for listeners whose absolute thresholds at 4 kHz exceeded 7.5 dB HL. No such elevations were observed in conditions having no binaural cues available to aid detection (i.e., "monaural" conditions). Partitioning and analyses of the data revealed that those elevated thresholds (1) were more attributable to hearing level than to age and (2) result from increased levels of internal noise. The data suggest that listeners whose high-frequency monaural hearing status would be classified audiometrically as being normal or "slight loss" may exhibit substantial and perceptually meaningful losses of binaural processing.

Audiometrically-defined “slight” or “hidden” hearing losses can be manifested as changes in binaural detection

We hypothesized that audiometrically-defined “slight” or “hidden” hearing losses might be associated with losses in binaural detection via degradations in precision of coding of interaural temporal disparities (ITDs). Thirty-one listeners were tested using masking configurations that, taken together, allow one to describe how precision of ITD-coding varies as a function of reference ITD and center frequency. Binaural detection thresholds at 500 Hz and 4 kHz were found to increase magnitude of ITD, consistent with there being a loss of precision of ITD-coding that increases with magnitude of ITD. Binaural detection thresholds were elevated, across all ITDs, for those listeners whose absolute thresholds at 4 kHz exceeded 7.5 dB HL, but were not greater than 23 dB HL. No such elevations were observed in conditions having no binaural cues available to aid detection (i.e., “monaural” conditions). Partitioning and analyses of the data revealed the elevated thresholds: 1) were more attributable to hearing level than to age; 2) result from increased levels of internal binaural-processing noise. Our conclusion is that listeners whose high-frequency monaural hearing status would be classified audiometrically as being normal or “slight loss” could still suffer from perceptually meaningful losses of binaural processing.

The across frequency independence of equalization of interaural time delay in the equalization-cancellation model of binaural unmasking.

The equalization stage in the equalization-cancellation model of binaural unmasking compensates for the interaural time delay (ITD) of a masking noise by introducing an opposite, internal delay [N. I. Durlach, in Foundations of Modern Auditory Theory, Vol. II., edited by J. V. Tobias (Academic, New York, 1972)]. Culling and Summerfield [J. Acoust. Soc. Am. 98, 785-797 (1995)] developed a multi-channel version of this model in which equalization was "free" to use the optimal delay in each channel. Two experiments were conducted to test if equalization was indeed free or if it was "restricted" to the same delay in all channels. One experiment measured binaural detection thresholds, using an adaptive procedure, for 1-, 5-, or 17-component tones against a broadband masking noise, in three binaural configurations (N0S180, N180S0, and N90S270). The thresholds for the 1-component stimuli were used to normalize the levels of each of the 5- and 17-component stimuli so that they were equally detectable. If equalization was restricted, then, for the 5- and 17-component stimuli, the N90S270 and N180S0 configurations would yield a greater threshold than the N0S180 configurations. No such difference was found. A subsequent experiment measured binaural detection thresholds, via psychometric functions, for a 2-component complex tone in the same three binaural configurations. Again, no differential effect of configuration was observed. An analytic model of the detection of a complex tone showed that the results were more consistent with free equalization than restricted equalization, although the size of the differences was found to depend on the shape of the psychometric function for detection.

Lateralization and detection of low-frequency binaural stimuli: Effects of distribution of internal delay

The position-variable model [R. M. Stern, Jr., and H. S. Colburn, J. Acoust. Soc. Am. 64, 127–140 (1978)], which had been developed to describe binaural phenomena at 500 Hz, is extended to describe and predict binaural lateralization and detection phenomena at frequencies of 250–1200 Hz. The major modification made to the model is the use of a frequency-dependent form of the function that describes the relative number of binaural coincidence detectors in the model as a function of their internal delay. This function is fitted to describe the lateralization of pure tones with a fixed ITD over a range of frequencies, and the ratio of N0Sπ to NπS0 binaural detection thresholds. The extended model describes without further modification the general dependence of the lateral position of pure tones on ITD and frequency, the lateralization of amplitude-modulated tones, and the ‘‘dominant region’’ lateralization phenomenon.

Binaural processing after corrected congenital unilateral conductive hearing loss

Binaural processing was measured in a series of tests in patients before and after surgery to correct congenital unilateral conductive hearing losses. Data are presented from 19 patients between the ages of 6 and 33 years that had an abnormal external and/or middle ear on one side but normal hearing in the other ear. Surgery improved thresholds an average of 36 dB HL (from 56 to 20 dB HL). Patients were tested pre- and postoperatively for interaural temporal difference limens, alternate and simultaneous loudness balances, sound localization, binaural detection thresholds, and speech perception in noise. There was statistically significant improvement after surgery in all tests, and the amount of improvement varied along a continuum that appears to be related to the simplicity of the task. For example, most postoperative patients had normal or near-normal performance in a test of interaural temporal difference limens, while almost all had difficulty localizing sounds. Neither binaural performance (before or after surgery) nor the improvement in performance was correlated with age, pure-tone thresholds, or asymmetry. Limited available data show no significant changes in performance from four weeks to over 24 weeks after surgery. In conclusion, binaural ability following corrective surgery exists in varying degrees in these tasks, suggesting different effects of abnormal early experience on different aspects of binaural hearing.