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Lerud KD, Hancock R, Skoe E. A high-density EEG and structural MRI source analysis of the frequency following response to missing fundamental stimuli reveals subcortical and cortical activation to low and high frequency stimuli. Neuroimage 2023; 279:120330. [PMID: 37598815 DOI: 10.1016/j.neuroimage.2023.120330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 07/29/2023] [Accepted: 08/14/2023] [Indexed: 08/22/2023] Open
Abstract
Pitch is a perceptual rather than physical phenomenon, important for spoken language use, musical communication, and other aspects of everyday life. Auditory stimuli can be designed to probe the relationship between perception and physiological responses to pitch-evoking stimuli. One technique for measuring physiological responses to pitch-evoking stimuli is the frequency following response (FFR). The FFR is an electroencephalographic (EEG) response to periodic auditory stimuli. The FFR contains nonlinearities not present in the stimuli, including correlates of the amplitude envelope of the stimulus; however, these nonlinearities remain undercharacterized. The FFR is a composite response reflecting multiple neural and peripheral generators, and their contributions to the scalp-recorded FFR vary in ill-understood ways depending on the electrode montage, stimulus, and imaging technique. The FFR is typically assumed to be generated in the auditory brainstem; there is also evidence both for and against a cortical contribution to the FFR. Here a methodology is used to examine the FFR correlates of pitch and the generators of the FFR to stimuli with different pitches. Stimuli were designed to tease apart biological correlates of pitch and amplitude envelope. FFRs were recorded with 256-electrode EEG nets, in contrast to a typical FFR setup which only contains a single active electrode. Structural MRI scans were obtained for each participant to co-register with the electrode locations and constrain a source localization algorithm. The results of this localization shed light on the generating mechanisms of the FFR, including providing evidence for both cortical and subcortical auditory sources.
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Affiliation(s)
- Karl D Lerud
- University of Maryland College Park, Institute for Systems Research, 20742, United States of America.
| | - Roeland Hancock
- Yale University, Wu Tsai Institute, 06510, United States of America
| | - Erika Skoe
- University of Connecticut, Department of Speech, Language, and Hearing Sciences, Cognitive Sciences Program, 06269, United States of America
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Abstract
OBJECTIVE The medial olivocochlear (MOC) reflex provides efferent feedback from the brainstem to cochlear outer hair cells. Physiologic studies have demonstrated that the MOC reflex is involved in "unmasking" of signals-in-noise at the level of the auditory nerve; however, its functional importance in human hearing remains unclear. DESIGN This study examined relationships between pre-neural measurements of MOC reflex strength (click-evoked otoacoustic emission inhibition; CEOAE) and neural measurements of speech-in-noise encoding (speech frequency following response; sFFR) in four conditions (Quiet, Contralateral Noise, Ipsilateral Noise, and Ipsilateral + Contralateral Noise). Three measures of CEOAE inhibition (amplitude reduction, effective attenuation, and input-output slope inhibition) were used to quantify pre-neural MOC reflex strength. Correlations between pre-neural MOC reflex strength and sFFR "unmasking" (i.e. response recovery from masking effects with activation of the MOC reflex in time and frequency domains) were assessed. STUDY SAMPLE 18 young adults with normal hearing. RESULTS sFFR unmasking effects were insignificant, and there were no correlations between pre-neural MOC reflex strength and sFFR unmasking in the time or frequency domain. CONCLUSION Our results do not support the hypothesis that the MOC reflex is involved in speech-in-noise neural encoding, at least for features that are represented in the sFFR at the SNR tested.
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Affiliation(s)
- S B Smith
- Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, TX, USA
| | - B Cone
- Department of Speech, Language, and Hearing Sciences, University of Arizona, Tucson, AZ, USA
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Brainstem correlates of cochlear nonlinearity measured via the scalp-recorded frequency-following response. Neuroreport 2020; 31:702-707. [PMID: 32453027 DOI: 10.1097/wnr.0000000000001452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The frequency-following response (FFR) is an EEG-based potential used to characterize the brainstem encoding of complex sounds. Adopting techniques from auditory signal processing, we assessed the degree to which FFRs encode important properties of cochlear processing (e.g. nonlinearities) and their relation to speech-in-noise (SIN) listening skills. Based on the premise that normal cochlear transduction is characterized by rectification and compression, we reasoned these nonlinearities would create measurable harmonic distortion in FFRs in response to even pure tone input. We recorded FFRs to nonspeech (pure- and amplitude-modulated-tones) stimuli in normal-hearing individuals. We then compared conventional indices of cochlear nonlinearity, via distortion product otoacoustic emission (DPOAE) I/O functions, to total harmonic distortion measured from neural FFRs (FFRTHD). Analysis of DPOAE growth and the FFRTHD revealed listeners with higher cochlear compression thresholds had lower neural FFRTHD distortion (i.e. more linear FFRs), thus linking cochlear and brainstem correlates of auditory nonlinearity. Importantly, FFRTHD was also negatively correlated with SIN perception whereby listeners with higher FFRTHD (i.e. more nonlinear responses) showed better performance on the QuickSIN. We infer individual differences in SIN perception and FFR nonlinearity even in normal-hearing individuals may reflect subtle differences in auditory health and suprathreshold hearing skills not captured by normal audiometric evaluation. Future studies in hearing-impaired individuals and animal models are necessary to confirm the diagnostic utility of FFRTHD and its relation to cochlear hearing loss or peripheral neurodegeneration in humans.
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Cheng LH, Wang CH, Lu RH, Chen YF. Evaluating the Function of the Medial Olivocochlear Bundle in Patients With Bilateral Tinnitus. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2020; 63:1969-1978. [PMID: 32511051 DOI: 10.1044/2020_jslhr-19-00080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Purpose No study has investigated the effects of contralateral noise (CN) on speech-in-noise perception (SINP) in listeners with tinnitus. The mechanisms underlying the involvement of medial olivocochlear (MOC) reflex with SINP remain to be elucidated. This study aimed to investigate the MOC function in patients with bilateral tinnitus by measuring distortion product otoacoustic emission and SINP. Method Eighteen patients with bilateral tinnitus (one male and 17 females; age: M ± SD = 45.61 ± 10.18 years) and 19 listeners without tinnitus (six males and 13 females; age: M ± SD = 34.11 ± 8.35 years) were recruited for the study. Each subject underwent distortion product otoacoustic emission measurement and the SINP test for both ears. The effects of CN on these two measurements were compared between tinnitus ears (TEs) and no-tinnitus ears (NTEs). Results The presence of CN significantly reduced distortion product (DP) amplitudes and improved SINP for TEs, and the amounts of DP suppression and SINP improvement were similar to those in NTEs. Improvement of SINP was positively correlated with DP suppression at 6185 Hz for NTEs and at 1640 Hz for TEs. Conclusions The results of this study suggest that the amounts of DP suppression and SINP improvement were similar between listeners with and without tinnitus. For both ear groups, the MOC reflex was involved with SINP at specific frequencies. Any clinical test outcomes with regard to the MOC bundle in patients with tinnitus should be interpreted with caution until further studies are conducted.
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Affiliation(s)
- Lin-Hua Cheng
- Department of Speech-Language Pathology and Audiology, National Taipei University of Nursing and Health Sciences, Taiwan
| | - Chih-Hung Wang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan
- Taichung Armed Forces General Hospital, Taiwan
| | - Rou-Huei Lu
- Taichung Armed Forces General Hospital, Taiwan
| | - Yu-Fu Chen
- Department of Speech-Language Pathology and Audiology, National Taipei University of Nursing and Health Sciences, Taiwan
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5
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A novel signal processing approach to auditory phantom perception. Psychon Bull Rev 2018; 26:250-260. [PMID: 30066082 DOI: 10.3758/s13423-018-1513-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The ear and brain interact in an orchestrated manner to create sensations of phantom tones that are audible to listeners despite lacking physical presence in original sounds. The relative contribution of peripheral sensory cell activity and cortical mechanisms to phantom hearing remains elusive. The current study addressed the question of whether non-linear components of a complex signal exist that are not captured by the linear combination of cosines in a series. To this end, we investigated the source and spectro-temporal dynamics of non-linear components within two-tone complexes related to phantom acoustic perception. The empirical mode decomposition, a method for non-linear and non-stationary processes, was applied to extract the extra-aural existence of an oscillatory component within the original signal associated with the phantom sound. This travelling wave (phantom) has never before been observed in the sound's linear spectrum. We showed that the wave travels at a velocity that accurately maps onto the perceived phantom tone frequency. Phase coherence of oscillatory mode dynamics predicted discrimination sensitivity to phantom sounds by listeners. Perceived incidences of phantom tones correlated with magnitude of the Hilbert power spectra of the extra-aural component. Findings suggest a possible origin of phantom sounds that exists within the original signal, with potential implications for current models of non-linear cochlear mechanics and cortical dynamics in generating phantom percepts.
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Smith SB, Ichiba K, Velenovsky DS, Cone B. Efferent modulation of pre-neural and neural distortion products. Hear Res 2017; 356:25-34. [PMID: 29122423 PMCID: PMC5705265 DOI: 10.1016/j.heares.2017.10.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 10/17/2017] [Accepted: 10/24/2017] [Indexed: 01/18/2023]
Abstract
Distortion product otoacoustic emissions (DPOAEs) and distortion product frequency following responses (DPFFRs) are respectively pre-neural and neural measurements associated with cochlear nonlinearity. Because cochlear nonlinearity is putatively linked to outer hair cell electromotility, DPOAEs and DPFFRs may provide complementary measurements of the human medial olivocochlear (MOC) reflex, which directly modulates outer hair cell function. In this study, we first quantified MOC reflex-induced DPOAE inhibition at spectral fine structure peaks in 22 young human adults with normal hearing. The f1 and f2 tone pairs producing the largest DPOAE fine structure peak for each subject were then used to evoke DPFFRs with and without MOC reflex activation to provide a related neural measure of efferent inhibition. We observed significant positive relationships between DPOAE fine structure peak inhibition and inhibition of DPFFR components representing neural phase locking to f2 and 2f1-f2, but not f1. These findings may support previous observations that the MOC reflex inhibits DPOAE sources differentially. That these effects are maintained and represented in the auditory brainstem suggests that the MOC reflex may exert a potent influence on subsequent subcortical neural representation of sound.
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Affiliation(s)
- S B Smith
- University of Arizona, Department of Speech, Language, and Hearing Sciences, Tucson, AZ, USA.
| | - K Ichiba
- University of Arizona, Department of Speech, Language, and Hearing Sciences, Tucson, AZ, USA
| | - D S Velenovsky
- University of Arizona, Department of Speech, Language, and Hearing Sciences, Tucson, AZ, USA
| | - B Cone
- University of Arizona, Department of Speech, Language, and Hearing Sciences, Tucson, AZ, USA
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Lerud KD, Almonte FV, Kim JC, Large EW. Mode-locking neurodynamics predict human auditory brainstem responses to musical intervals. Hear Res 2013; 308:41-9. [PMID: 24091182 DOI: 10.1016/j.heares.2013.09.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 09/13/2013] [Accepted: 09/17/2013] [Indexed: 11/25/2022]
Abstract
The auditory nervous system is highly nonlinear. Some nonlinear responses arise through active processes in the cochlea, while others may arise in neural populations of the cochlear nucleus, inferior colliculus and higher auditory areas. In humans, auditory brainstem recordings reveal nonlinear population responses to combinations of pure tones, and to musical intervals composed of complex tones. Yet the biophysical origin of central auditory nonlinearities, their signal processing properties, and their relationship to auditory perception remain largely unknown. Both stimulus components and nonlinear resonances are well represented in auditory brainstem nuclei due to neural phase-locking. Recently mode-locking, a generalization of phase-locking that implies an intrinsically nonlinear processing of sound, has been observed in mammalian auditory brainstem nuclei. Here we show that a canonical model of mode-locked neural oscillation predicts the complex nonlinear population responses to musical intervals that have been observed in the human brainstem. The model makes predictions about auditory signal processing and perception that are different from traditional delay-based models, and may provide insight into the nature of auditory population responses. We anticipate that the application of dynamical systems analysis will provide the starting point for generic models of auditory population dynamics, and lead to a deeper understanding of nonlinear auditory signal processing possibly arising in excitatory-inhibitory networks of the central auditory nervous system. This approach has the potential to link neural dynamics with the perception of pitch, music, and speech, and lead to dynamical models of auditory system development.
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Affiliation(s)
- Karl D Lerud
- University of Connecticut, Department of Psychology, 406 Babbidge Road, Storrs, CT 06269-1020, USA
| | - Felix V Almonte
- University of Connecticut, Department of Psychology, 406 Babbidge Road, Storrs, CT 06269-1020, USA
| | - Ji Chul Kim
- University of Connecticut, Department of Psychology, 406 Babbidge Road, Storrs, CT 06269-1020, USA
| | - Edward W Large
- University of Connecticut, Department of Psychology, 406 Babbidge Road, Storrs, CT 06269-1020, USA.
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Bidelman GM, Hutka S, Moreno S. Tone language speakers and musicians share enhanced perceptual and cognitive abilities for musical pitch: evidence for bidirectionality between the domains of language and music. PLoS One 2013; 8:e60676. [PMID: 23565267 PMCID: PMC3614545 DOI: 10.1371/journal.pone.0060676] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 03/01/2013] [Indexed: 11/19/2022] Open
Abstract
Psychophysiological evidence suggests that music and language are intimately coupled such that experience/training in one domain can influence processing required in the other domain. While the influence of music on language processing is now well-documented, evidence of language-to-music effects have yet to be firmly established. Here, using a cross-sectional design, we compared the performance of musicians to that of tone-language (Cantonese) speakers on tasks of auditory pitch acuity, music perception, and general cognitive ability (e.g., fluid intelligence, working memory). While musicians demonstrated superior performance on all auditory measures, comparable perceptual enhancements were observed for Cantonese participants, relative to English-speaking nonmusicians. These results provide evidence that tone-language background is associated with higher auditory perceptual performance for music listening. Musicians and Cantonese speakers also showed superior working memory capacity relative to nonmusician controls, suggesting that in addition to basic perceptual enhancements, tone-language background and music training might also be associated with enhanced general cognitive abilities. Our findings support the notion that tone language speakers and musically trained individuals have higher performance than English-speaking listeners for the perceptual-cognitive processing necessary for basic auditory as well as complex music perception. These results illustrate bidirectional influences between the domains of music and language.
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Affiliation(s)
- Gavin M. Bidelman
- Institute for Intelligent Systems, University of Memphis, Memphis, Tennessee, United States of America
- School of Communication Sciences & Disorders, University of Memphis, Memphis, Tennessee, United States of America
- * E-mail:
| | - Stefanie Hutka
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada
| | - Sylvain Moreno
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada
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Gockel HE, Farooq R, Muhammed L, Plack CJ, Carlyon RP. Differences between psychoacoustic and frequency following response measures of distortion tone level and masking. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2012; 132:2524-2535. [PMID: 23039446 PMCID: PMC5777604 DOI: 10.1121/1.4751541] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The scalp-recorded frequency following response (FFR) in humans was measured for a 244-Hz pure tone at a range of input levels and for complex tones containing harmonics 2-4 of a 300-Hz fundamental, but shifted by ±56 Hz. The effective magnitude of the cubic difference tone (CDT) and the quadratic difference tone (QDT, at F(2)-F(1)) in the FFR for the complex was estimated by comparing the magnitude spectrum of the FFR at the distortion product (DP) frequency with that for the pure tone. The effective DP levels in the FFR were higher than those commonly estimated in psychophysical experiments, indicating contributions to the DP in the FFR in addition to the audible propagated component. A low-frequency narrowband noise masker reduced the magnitude of FFR responses to the CDT but also to primary components over a wide range of frequencies. The results indicate that audible DPs may contribute very little to the DPs observed in the FFR and that using a narrowband noise for the purpose of masking audible DPs can have undesired effects on the FFR over a wide frequency range. The results are consistent with the notion that broadly tuned mechanisms central to the auditory nerve strongly influence the FFR.
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Affiliation(s)
- Hedwig E Gockel
- MRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom.
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10
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Smalt CJ, Krishnan A, Bidelman GM, Ananthakrishnan S, Gandour JT. Distortion products and their influence on representation of pitch-relevant information in the human brainstem for unresolved harmonic complex tones. Hear Res 2012; 292:26-34. [PMID: 22910032 PMCID: PMC3483078 DOI: 10.1016/j.heares.2012.08.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 07/31/2012] [Accepted: 08/02/2012] [Indexed: 11/29/2022]
Abstract
Pitch experiments aimed at evaluating temporal pitch mechanism(s) often utilize complex sounds with only unresolved harmonic components, and a low-pass noise masker to eliminate the potential contribution of audible distortion products to the pitch percept. Herein we examine how: (i) masker induced reduction of neural distortion products (difference tone: DT; and cubic difference tone: CDT) alters the representation of pitch relevant information in the brainstem; and (ii) the pitch salience is altered when distortion products are reduced and/or eliminated. Scalp recorded brainstem frequency following responses (FFR) were recorded in normal hearing individuals using a complex tone with only unresolved harmonics presented in quiet, and in the presence of a low-pass masker at SNRs of +15, +5, and -5 dB. Difference limen for F0 discrimination (F0 DL) was obtained in quiet and in the presence of low-pass noise. Magnitude of DT components (with the exception of components at F0 and 2F0), and the CDT components decreased with increasing masker level. Neural pitch strength decreased with increasing masker level for both the envelope-related (FFR(ENV)) and spectral-related (FFR(SPEC)) phase-locked activity. Finally, F0 DLs increased with decreasing SNRs suggesting poorer F0 discrimination with reduction of the distortion products. Collectively, these findings support the notion that both DT and CDT, as reflected in the FFR(ENV) and FFR(SPEC), respectively, influence both the brainstem representation of pitch relevant information and the pitch salience of the complex sounds.
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Affiliation(s)
- Christopher J. Smalt
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Ananthanarayan Krishnan
- Department of Speech, Language, Hearing Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Gavin M. Bidelman
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, ON, M6A 2E1, Canada
| | - Saradha Ananthakrishnan
- Department of Speech, Language, Hearing Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Jackson T. Gandour
- Department of Speech, Language, Hearing Sciences, Purdue University, West Lafayette, Indiana, USA
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Bhagat SP, Carter PH. Efferent-induced change in human cochlear compression and its influence on masking of tones. Neurosci Lett 2010; 485:94-7. [PMID: 20813158 DOI: 10.1016/j.neulet.2010.08.069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 08/25/2010] [Indexed: 10/19/2022]
Abstract
Several lines of evidence suggest that medial olivocochlear (MOC) efferent neurons modify cochlear output to improve signal detection in noise. In animal models, stimulation of MOC efferents reduces the amount of compression in basilar membrane (BM) growth functions. Linearization of BM growth functions may assist in extending the neural response to the signal above that of noise, leading to a decrease in masking. In order to test this hypothesis, effects of MOC efferent neurons on BM compression were studied indirectly in humans by examining the effects of contralateral noise on distortion-product otoacoustic emission (DPOAE) input-output functions at 1.0 and 2.0kHz. Compression threshold estimates from a three-segment linear regression model applied to the DPOAE functions were derived in order to determine correlations with psychophysical measurements of masking of tones at 1.0 and 2.0kHz. Contralateral noise shifted the DPOAE compression threshold to a significantly higher level at 1.0kHz, but not at 2.0kHz. A significant negative correlation between the change in DPOAE compression threshold and the amount of masking at 1.0kHz was observed, but no correlation between these variables was detected at 2.0kHz. The results of this experiment at the lower test frequency indicated that contralateral noise linearized DPOAE input-output functions, and individuals with larger DPOAE compression threshold shifts tended to exhibit less masking. Under certain conditions, decreases in cochlear compression induced by MOC efferent neurons may lead to unmasking of tones presented in noise.
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Affiliation(s)
- Shaum P Bhagat
- Hearing Science Laboratory, School of Audiology and Speech-Language Pathology, The University of Memphis, 807 Jefferson Avenue, Memphis, TN 38105, United States.
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Si W, Wang J, Tsang KM, Chan WL. Harmonics and intermodulation in subthreshold FitzHugh-Nagumo neuron. CHAOS (WOODBURY, N.Y.) 2009; 19:033144. [PMID: 19792024 DOI: 10.1063/1.3234239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Intermodulation and harmonics are important in frequency analysis of nonlinear systems. In neuron research, most investigations are taken in studying synchronization between the external stimuli and the output of neuron, but harmonics and intermodulation are often ignored. In this paper, harmonics and intermodulation of the subthreshold FitzHugh-Nagumo neuron are investigated and their magnitudes are used to predict frequency response of the neuron. Furthermore, through analyzing the magnitudes of harmonics, the intrinsic frequencies of the neuron could be identified.
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Affiliation(s)
- Wenjie Si
- School of Electrical and Automation Engineering, Tianjin University, Tianjin, China
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Elsisy H, Krishnan A. Comparison of the acoustic and neural distortion product at 2f1-f2 in normal-hearing adults. Int J Audiol 2008; 47:431-8. [PMID: 18574781 DOI: 10.1080/14992020801987396] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Input/output functions of the simultaneously recorded acoustic distortion product otoacoustic emissions (DPOAE) and neural frequency following-response distortion products (FFR-DP) at 2f1-f2 were evaluated to determine if these two representations of cochlear nonlinearity exhibit similar response behavior, which would suggest shared cochlear generators. Responses were recorded from normal-hearing adults for a tone burst stimulus pair (F1: 500 Hz; F2: 612 Hz) at 40-70 dB nHL. DPOAE responses were recorded from the ear canal, and FFR responses were recorded differentially from scalp electrodes, representing a vertical configuration. The input/output function for FFR-DP revealed a compressive saturating nonlinearity, whereas the DPOAE input/output function exhibited a linear growth at higher intensities following a compressive behavior at moderate levels. Results appear to suggest that cochlear generators may be contributing differentially to the acoustic and the neural distortion products. Also, FFR-DP responses appeared more identifiable and less variable, particularly at lower stimulus levels, than the corresponding DPOAE. These findings may point to a potential benefit of applying FFR testing to complement DPOAE in evaluating cochlear function at low frequencies.
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Affiliation(s)
- Hala Elsisy
- Auditory Electrophysiology Laboratory, Department of Speech Language and Hearing Sciences, Purdue University, West Lafayette, USA
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Wile D, Balaban E. An auditory neural correlate suggests a mechanism underlying holistic pitch perception. PLoS One 2007; 2:e369. [PMID: 17426817 PMCID: PMC1838520 DOI: 10.1371/journal.pone.0000369] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 03/08/2007] [Indexed: 11/18/2022] Open
Abstract
Current theories of auditory pitch perception propose that cochlear place (spectral) and activity timing pattern (temporal) information are somehow combined within the brain to produce holistic pitch percepts, yet the neural mechanisms for integrating these two kinds of information remain obscure. To examine this process in more detail, stimuli made up of three pure tones whose components are individually resolved by the peripheral auditory system, but that nonetheless elicit a holistic, "missing fundamental" pitch percept, were played to human listeners. A technique was used to separate neural timing activity related to individual components of the tone complexes from timing activity related to an emergent feature of the complex (the envelope), and the region of the tonotopic map where information could originate from was simultaneously restricted by masking noise. Pitch percepts were mirrored to a very high degree by a simple combination of component-related and envelope-related neural responses with similar timing that originate within higher-frequency regions of the tonotopic map where stimulus components interact. These results suggest a coding scheme for holistic pitches whereby limited regions of the tonotopic map (spectral places) carrying envelope- and component-related activity with similar timing patterns selectively provide a key source of neural pitch information. A similar mechanism of integration between local and emergent object properties may contribute to holistic percepts in a variety of sensory systems.
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Affiliation(s)
- Daryl Wile
- Behavioral Neurosciences Program, McGill University, Montreal, Canada
| | - Evan Balaban
- Behavioral Neurosciences Program, McGill University, Montreal, Canada
- Cognitive Neuroscience Sector, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
- * To whom correspondence should be addressed. E-mail:
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