Human interaural time difference thresholds for sine tones: The high-frequency limit

[EN] The smallest detectable interaural time difference (ITD) for sine tones was measured for four human listeners to determine the dependence on tone frequency. At low frequencies, 250 700 Hz, threshold ITDs were approximately inversely proportional to tone frequency. At mid-frequencies, 700 1000 Hz, threshold ITDs were smallest. At high frequencies, above 1000 Hz, thresholds increased faster than exponentially with increasing frequency becoming unmeasurably high justabove 1400 Hz. A model for ITD detection began with a biophysically based computational model for a medial superior olive (MSO) neuron that produced robust ITD responses up to 1000 Hz, and demonstrated a dramatic reduction in ITD-dependence from 1000 to 1500 Hz. Rate-ITD functions from the MSO model became inputs to binaural display models both place based and rate-differ-ence based. A place-based, centroid model with a rigid internal threshold reproduced almost all fea- tures of the human data. A signal-detection version of this model reproduced the high-frequence divergence but badly underestimated low-frequency thresholds. A rate-difference model incorporat- ing fast contralateral inhibition reproduced the major features of the human threshold data except for the divergence. A combined, hybrid model could reproduce all the threshold data.We are grateful to Dr. Les Bernstein for a useful discussion about the centroid display and to Dr. Steve Colburn for discussions about modeling. Zane Crawford provided valuable statistical help. This research was supported by The Vicerectorado de Profesorado y Ordenacion Academica of the Universitat Politecnica de Valencia (Spain), which brought L. D. to Michigan State, by the NIDCD Grant No. DC-00181 and the AFOSR Grant No. 11NL002. A. B. was supported by NIDCD Grant Nos. DC-00100 (H. S. Colburn) and P30-DC04663 (Core Center).Brughera, A.; Dunai ., L.; Hartmann, WM. (2013). Human interaural time difference thresholds for sine tones: The high-frequency limit. The Journal of the Acoustical Society of America. 133(5):2839-2855. https://doi.org/10.1121/1.4795778S28392855133

Sensory Communication

Contains table of contents for Section 2, an introduction and reports on twelve research projects.National Institutes of Health Grant R01 DC00117National Institutes of Health Grant R01 DC02032National Institutes of Health/National Institute of Deafness and Other Communication Disorders Grant 2 R01 DC00126National Institutes of Health Grant 2 R01 DC00270National Institutes of Health Contract N01 DC-5-2107National Institutes of Health Grant 2 R01 DC00100U.S. Navy - Office of Naval Research Grant N61339-96-K-0002U.S. Navy - Office of Naval Research Grant N61339-96-K-0003U.S. Navy - Office of Naval Research Grant N00014-97-1-0635U.S. Navy - Office of Naval Research Grant N00014-97-1-0655U.S. Navy - Office of Naval Research Subcontract 40167U.S. Navy - Office of Naval Research Grant N00014-96-1-0379U.S. Air Force - Office of Scientific Research Grant F49620-96-1-0202National Institutes of Health Grant RO1 NS33778Massachusetts General Hospital, Center for Innovative Minimally Invasive Therapy Research Fellowship Gran

Sensory Communication

Contains table of contents for Section 2, an introduction and reports on fourteen research projects.National Institutes of Health Grant RO1 DC00117National Institutes of Health Grant RO1 DC02032National Institutes of Health/National Institute on Deafness and Other Communication Disorders Grant R01 DC00126National Institutes of Health Grant R01 DC00270National Institutes of Health Contract N01 DC52107U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-95-K-0014U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-96-K-0003U.S. Navy - Office of Naval Research Grant N00014-96-1-0379U.S. Air Force - Office of Scientific Research Grant F49620-95-1-0176U.S. Air Force - Office of Scientific Research Grant F49620-96-1-0202U.S. Navy - Office of Naval Research Subcontract 40167U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-96-K-0002National Institutes of Health Grant R01-NS33778U.S. Navy - Office of Naval Research Grant N00014-92-J-184

Sensory Communication

Contains table of contents for Section 2, an introduction and reports on fifteen research projects.National Institutes of Health Grant RO1 DC00117National Institutes of Health Grant RO1 DC02032National Institutes of Health Contract P01-DC00361National Institutes of Health Contract N01-DC22402National Institutes of Health/National Institute on Deafness and Other Communication Disorders Grant 2 R01 DC00126National Institutes of Health Grant 2 R01 DC00270National Institutes of Health Contract N01 DC-5-2107National Institutes of Health Grant 2 R01 DC00100U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-94-C-0087U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-95-K-0014U.S. Navy - Office of Naval Research/Naval Air Warfare Center Grant N00014-93-1-1399U.S. Navy - Office of Naval Research/Naval Air Warfare Center Grant N00014-94-1-1079U.S. Navy - Office of Naval Research Subcontract 40167U.S. Navy - Office of Naval Research Grant N00014-92-J-1814National Institutes of Health Grant R01-NS33778U.S. Navy - Office of Naval Research Grant N00014-88-K-0604National Aeronautics and Space Administration Grant NCC 2-771U.S. Air Force - Office of Scientific Research Grant F49620-94-1-0236U.S. Air Force - Office of Scientific Research Agreement with Brandeis Universit

Sensitivity to interaural time differences across sound frequency: models of auditory-brainstem neurons

Normal-hearing listeners can locate sound sources, using binaural cues for azimuth angle. These binaural differences in the timing and intensity of sound arriving at the two ears, interaural time differences (ITDs) and interaural intensity differences (IIDs), also support selective listening in multi-talker environments. Auditory-brainstem neurons of the medial superior olive (MSO) and lateral superior olive (LSO) encode ITD in the envelope of sound (ITDENV) and in the temporal fine structure of low-frequency sound (ITDTFS); LSO neurons encode IID. Bilateral-cochlear-implant (bCI) listeners generally receive only IID and ITDENV. Experimental bCI pulse-bursts overcome adaptation, and convey electrical ITDTFS. Improving the understanding of mechanisms for ITD sensitivity can help bCI developers convey acoustic ITDTFS. In this dissertation, models for auditory-brainstem neurons are developed that explain human ability to detect small differences in ITD, as neuronal and MSO population mechanisms. Promoting binaural-coincidence detection and limiting backpropagation, model MSO ion-channels set resting potentials that reproduce dendritic and somatic KLT activation, somatic Na+ inactivation, and a lower amount of axonal Na+ inactivation. Sensitivity to ITDTFS in moderately fast and very fast model MSO neurons collectively match physiological data from 150 to 2000 Hz. The best-ITD (the ITD of highest spike rate) can be made contralateral-leading, by contralateral inhibition of moderate speed, or by asymmetric axon location, leveraging dendritic filtering. Leveraging standard binaural-display models, neuronal populations based on these model MSO neurons match normal-hearing human discrimination thresholds for ITDTFS in sine tones from 39 to 1500 Hz. Adaptation before binaural interaction helps model MSO neurons glimpse the ITDTFS of sound direct from a source, before reflected sound arrives from different directions. With inputs from adapting model spherical bushy cells, a moderately fast model MSO neuron reproduces in vivo responses to amplitude-modulated binaural beats, with a frequency-dependent emphasis of rising vs. peak sound-pressure for ITDTFS encoding, which reflects human ITD detection and reverberation times in outdoor environments. Distinct populations of model LSO neurons, spanning the range of electrical membrane impedance as a function of frequency in LSO neurons, collectively reflect discrimination thresholds for ITDENV in transposed tones across carrier frequency (4-10 kHz) and modulation rate (32-800 Hz).2022-09-28T00:00:00

Sensitivity to Envelope Interaural Time Differences: Modeling Auditory Modulation Filtering

For amplitude-modulated sound, the envelope interaural time difference (ITDENV) is a potential cue for sound-source location. ITDENV is encoded in the lateral superior olive (LSO) of the auditory brainstem, by excitatory-inhibitory (EI) neurons receiving ipsilateral excitation and contralateral inhibition. Between human listeners, sensitivity to ITDENV varies considerably, but ultimately decreases with increasing stimulus carrier frequency, and decreases more strongly with increasing modulation rate. Mechanisms underlying the variation in behavioral sensitivity remain unclear. Here, with increasing carrier frequency (4–10 kHz), as we phenomenologically model the associated decrease in ITDENV sensitivity using arbitrarily fewer neurons consistent across populations, we computationally model the variable sensitivity across human listeners and modulation rates (32–800 Hz) as the decreasing range of membrane frequency responses in LSO neurons. Transposed tones stimulate a bilateral auditory-periphery model, driving model EI neurons where electrical membrane impedance filters the frequency content of inputs driven by amplitude-modulated sound, evoking modulation filtering. Calculated from Fisher information in spike-rate functions of ITDENV, for model EI neuronal populations distinctly reflecting the LSO range in membrane frequency responses, just-noticeable differences in ITDENV collectively reproduce the largest variation in ITDENV sensitivity across human listeners. These slow to fast model populations each generally match the best human ITDENV sensitivity at a progressively higher modulation rate, by membrane-filtering and spike-generation properties producing realistically less than Poisson variance. Non-resonant model EI neurons are also sensitive to interaural intensity differences. With peripheral filters centered between carrier frequency and modulation sideband, fast resonant model EI neurons extend ITDENV sensitivity above 500-Hz modulation.Fil: Brughera, Andrew. Boston University; Estados Unidos. Macquarie University; AustraliaFil: Ballestero, Jimena Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: McAlpine, David. Macquarie University; Australi

Physiological and Psychophysical Modeling of the Precedence Effect

Many past studies of sound localization explored the precedence effect (PE), in which a pair of brief, temporally close sounds from different directions is perceived as coming from a location near that of the first-arriving sound. Here, a computational model of low-frequency inferior colliculus (IC) neurons accounts for both physiological and psychophysical responses to PE click stimuli. In the model, IC neurons have physiologically plausible inputs, receiving excitation from the ipsilateral medial superior olive (MSO) and long-lasting inhibition from both ipsilateral and contralateral MSOs, relayed through the dorsal nucleus of the lateral lemniscus. In this model, physiological suppression of the lagging response depends on the inter-stimulus delay (ISD) between the lead and lag as well as their relative locations. Psychophysical predictions are generated from a population of model neurons. At all ISDs, predicted lead localization is good. At short ISDs, the estimated location of the lag is near that of the lead, consistent with subjects perceiving both lead and lag from the lead location. As ISD increases, the estimated lag location moves closer to the true lag location, consistent with listeners’ perception of two sounds from separate locations. Together, these simulations suggest that location-dependent suppression in IC neurons can explain the behavioral phenomenon known as the precedence effect

Models of Brainstem Responses to Bilateral Electrical Stimulation

A simple, biophysically specified cell model is used to predict responses of binaurally sensitive neurons to patterns of input spikes that represent stimulation by acoustic and electric waveforms. Specifically, the effects of changes in parameters of input spike trains on model responses to interaural time difference (ITD) were studied for low-frequency periodic stimuli, with or without amplitude modulation. Simulations were limited to purely excitatory, bilaterally driven cell models with basic ionic currents and multiple input fibers. Parameters explored include average firing rate, synchrony index, modulation frequency, and latency dispersion of the input trains as well as the excitatory conductance and time constant of individual synapses in the cell model. Results are compared to physiological recordings from the inferior colliculus (IC) and discussed in terms of ITD-discrimination abilities of listeners with cochlear implants. Several empirically observed aspects of ITD sensitivity were simulated without evoking complex neural processing. Specifically, our results show saturation effects in rate–ITD curves, the absence of sustained responses to high-rate unmodulated pulse trains, the renewal of sensitivity to ITD in high-rate trains when inputs are amplitude-modulated, and interactions between envelope and fine-structure delays for some modulation frequencies