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Christopher A. Shera, PhD

TitleProfessor of Research Otolaryngology-Head & Neck Surgery
InstitutionUniversity of Southern California
DepartmentOtolaryngology
Phone+1 323 865 1685
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    Lab Site:

    http://apg.mechanicsofhearing.org


    The peripheral auditory system transforms air-borne pressure waves into neural impulses that are interpreted by the brain as sound and speech. The cochlea of the inner ear is a snail-shaped electro-hydromechanical signal amplifier, frequency analyzer, and transducer with an astounding constellation of performance characteristics, including sensitivity to sub-atomic displacements with microsecond mechanical response times; wideband operation spanning three orders-of-magnitude in frequency; an input dynamic range of 120 dB, corresponding to a million-million-fold change in signal energy; useful operation even at signal powers 100 times smaller than the background noise; and ultra-low power consumption (15 µW). All of this is achieved not with the latest silicon technology or by exploiting the power of quantum computers — neither has yet approached the performance of the ear — but by self-maintaining biological tissue, most of which is salty water. How does the ear do it?

    The Auditory Physics Group studies how the ear amplifies, analyzes, and creates sound. The goal is not only to understand how the cochlea achieves its astounding sensitivity and dynamic range but to use that knowledge to enhance the power of noninvasive probes of peripheral auditory function (e.g., otoacoustic emissions). Our approach involves a strong, quantitative interplay between theoretical modeling studies and physiological measurements. Ongoing work in the lab focuses on models of cochlear amplification, mechanisms of OAE generation, middle-ear transmission, and comparative studies of cochlear mechanics.


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    Collapse Research Activities and Funding
    Otoacoustic Emissions: Evoking the Future
    NIH/NIDCD R13DC016825Sep 19, 2017 - Aug 31, 2018
    Role: Principal Investigator
    11th International Mechanics of Hearing Workshop
    NIH/NIDCD R13DC010930Aug 1, 2010 - Jul 31, 2011
    Role: Principal Investigator
    Understanding Otoacoustic Emissions
    NIH/NIDCD R01DC003687Jan 1, 1999 - Dec 31, 2018
    Role: Principal Investigator
    MEASURING THE GAIN OF THE COCHLEAR AMPLIFIER
    NIH/NIDCD R03DC003494Sep 1, 1997 - Aug 31, 2000
    Role: Principal Investigator
    MEASURING THE GAIN OF THE COCHLEAR AMPLIFIER
    NIH/NIDCD F32DC000108Nov 1, 1994
    Role: Principal Investigator

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    Publications listed below are automatically derived from MEDLINE/PubMed and other sources, which might result in incorrect or missing publications. Researchers can login to make corrections and additions, or contact us for help.
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    1. Sumner CJ, Wells TT, Bergevin C, Sollini J, Kreft HA, Palmer AR, Oxenham AJ, Shera CA. Mammalian behavior and physiology converge to confirm sharper cochlear tuning in humans. Proc Natl Acad Sci U S A. 2018 Oct 15. PMID: 30322908.
      View in: PubMed
    2. Shera CA, Charaziak KK. Cochlear Frequency Tuning and Otoacoustic Emissions. Cold Spring Harb Perspect Med. 2018 Jul 23. PMID: 30037987.
      View in: PubMed
    3. Charaziak KK, Siegel JH, Shera CA. Spectral Ripples in Round-Window Cochlear Microphonics: Evidence for Multiple Generation Mechanisms. J Assoc Res Otolaryngol. 2018 Jul 16. PMID: 30014309.
      View in: PubMed
    4. Abdala C, Ortmann AJ, Shera CA. Reflection- and Distortion-Source Otoacoustic Emissions: Evidence for Increased Irregularity in the Human Cochlea During Aging. J Assoc Res Otolaryngol. 2018 Jul 02. PMID: 29968098.
      View in: PubMed
    5. Charaziak KK, Dong W, Shera CA. Temporal Suppression of Clicked-Evoked Otoacoustic Emissions and Basilar-Membrane Motion in Gerbils. AIP Conf Proc. 2018; 1965(1). PMID: 30057432.
      View in: PubMed
    6. Christensen AT, Abdala C, Shera CA. Probing Apical-Basal Differences in the Human Cochlea Using Distortion-Product Otoacoustic Emission Phase. AIP Conf Proc. 2018 May 31; 1965(1). PMID: 30089933.
      View in: PubMed
    7. Moleti A, Sisto R, Shera CA. Introducing Causality Violation for Improved DPOAE Component Unmixing. AIP Conf Proc. 2018 May 31; 1965(1). PMID: 30089934.
      View in: PubMed
    8. Gruters KG, Murphy DLK, Jenson CD, Smith DW, Shera CA, Groh JM. The eardrums move when the eyes move: A multisensory effect on the mechanics of hearing. Proc Natl Acad Sci U S A. 2018 Feb 06; 115(6):E1309-E1318. PMID: 29363603.
      View in: PubMed
    9. Abdala C, Guardia YC, Shera CA. Swept-tone stimulus-frequency otoacoustic emissions: Normative data and methodological considerations. J Acoust Soc Am. 2018 Jan; 143(1):181. PMID: 29390734.
      View in: PubMed
    10. Sisto R, Shera CA, Moleti A. Negative-delay sources in distortion product otoacoustic emissions. Hear Res. 2018 Mar; 360:25-30. PMID: 29287918.
      View in: PubMed
    11. Altoè A, Charaziak KK, Shera CA. Dynamics of cochlear nonlinearity: Automatic gain control or instantaneous damping? J Acoust Soc Am. 2017 Dec; 142(6):3510. PMID: 29289066.
      View in: PubMed
    12. Charaziak KK, Shera CA, Siegel JH. Using Cochlear Microphonic Potentials to Localize Peripheral Hearing Loss. Front Neurosci. 2017; 11:169. PMID: 28420953.
      View in: PubMed
    13. Abdala C, Luo P, Shera CA. Characterizing spontaneous otoacoustic emissions across the human lifespan. J Acoust Soc Am. 2017 Mar; 141(3):1874. PMID: 28372113.
      View in: PubMed
    14. Charaziak KK, Shera CA. Compensating for ear-canal acoustics when measuring otoacoustic emissions. J Acoust Soc Am. 2017 Jan; 141(1):515. PMID: 28147590.
      View in: PubMed
    15. Shera CA, Abdala C. Frequency shifts in distortion-product otoacoustic emissions evoked by swept tones. J Acoust Soc Am. 2016 Aug; 140(2):936. PMID: 27586726.
      View in: PubMed
    16. Verhulst S, Shera CA. Relating the Variability of Tone-Burst Otoacoustic Emission and Auditory Brainstem Response Latencies to the Underlying Cochlear Mechanics. AIP Conf Proc. 2015 Dec 31; 1703. PMID: 27175040.
      View in: PubMed
    17. Alkhairy SA, Shera CA. Increasing Computational Efficiency of Cochlear Models Using Boundary Layers. AIP Conf Proc. 2015 Dec 31; 1703. PMID: 27175041.
      View in: PubMed
    18. Abdala C, Luo P, Shera CA. Optimizing swept-tone protocols for recording distortion-product otoacoustic emissions in adults and newborns. J Acoust Soc Am. 2015 Dec; 138(6):3785-99. PMID: 26723333; PMCID: PMC4691260 [Available on 12/01/16].
    19. Shera CA. Iterated intracochlear reflection shapes the envelopes of basilar-membrane click responses. J Acoust Soc Am. 2015 Dec; 138(6):3717-22. PMID: 26723327.
      View in: PubMed
    20. Verhulst S, Bharadwaj HM, Mehraei G, Shera CA, Shinn-Cunningham BG. Functional modeling of the human auditory brainstem response to broadband stimulation. J Acoust Soc Am. 2015 Sep; 138(3):1637-59. PMID: 26428802; PMCID: PMC4592442.
    21. Shera CA. The spiral staircase: tonotopic microstructure and cochlear tuning. J Neurosci. 2015 Mar 18; 35(11):4683-90. PMID: 25788685; PMCID: PMC4363394.
    22. Sisto R, Moleti A, Shera CA. On the spatial distribution of the reflection sources of different latency components of otoacoustic emissions. J Acoust Soc Am. 2015 Feb; 137(2):768-76. PMID: 25698011; PMCID: PMC4336253.
    23. Shera CA. On the method of lumens. J Acoust Soc Am. 2014 Dec; 136(6):3126. PMID: 25480060; PMCID: PMC4281039.
    24. Marshall L, Lapsley Miller JA, Guinan JJ, Shera CA, Reed CM, Perez ZD, Delhorne LA, Boege P. Otoacoustic-emission-based medial-olivocochlear reflex assays for humans. J Acoust Soc Am. 2014 Nov; 136(5):2697-713. PMID: 25373970.
      View in: PubMed
    25. Knudson IM, Shera CA, Melcher JR. Increased contralateral suppression of otoacoustic emissions indicates a hyperresponsive medial olivocochlear system in humans with tinnitus and hyperacusis. J Neurophysiol. 2014 Dec 15; 112(12):3197-208. PMID: 25231612; PMCID: PMC4269714.
    26. Shera CA. Macromechanics of Hearing: The Unknown Known. AIP Conf Proc. 2014 Jun; 1703. PMID: 27630377.
      View in: PubMed
    27. Abdala C, Guérit F, Luo P, Shera CA. Distortion-product otoacoustic emission reflection-component delays and cochlear tuning: estimates from across the human lifespan. J Acoust Soc Am. 2014 Apr; 135(4):1950-8. PMID: 25234993; PMCID: PMC4167749.
    28. Kalluri R, Shera CA. Measuring stimulus-frequency otoacoustic emissions using swept tones. J Acoust Soc Am. 2013 Jul; 134(1):356-68. PMID: 23862813; PMCID: PMC3732205.
    29. Shera CA, Cooper NP. Basilar-membrane interference patterns from multiple internal reflection of cochlear traveling waves. J Acoust Soc Am. 2013 Apr; 133(4):2224-39. PMID: 23556591; PMCID: PMC4109360.
    30. Verhulst S, Dau T, Shera CA. Nonlinear time-domain cochlear model for transient stimulation and human otoacoustic emission. J Acoust Soc Am. 2012 Dec; 132(6):3842-8. PMID: 23231114; PMCID: PMC3528681.
    31. Shera CA, Bergevin C. Obtaining reliable phase-gradient delays from otoacoustic emission data. J Acoust Soc Am. 2012 Aug; 132(2):927-43. PMID: 22894215; PMCID: PMC3427360.
    32. Elliott SJ, Shera CA. The cochlea as a smart structure. Smart Mater Struct. 2012 Jun; 21(6):64001. PMID: 23148128.
      View in: PubMed
    33. Bergevin C, Walsh EJ, McGee J, Shera CA. Probing cochlear tuning and tonotopy in the tiger using otoacoustic emissions. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2012 Aug; 198(8):617-24. PMID: 22645048; PMCID: PMC3493156.
    34. Rasetshwane DM, Neely ST, Allen JB, Shera CA. Reflectance of acoustic horns and solution of the inverse problem. J Acoust Soc Am. 2012 Mar; 131(3):1863-73. PMID: 22423684; PMCID: PMC3316681.
    35. de Boer E, Shera CA, Nuttall AL. Tracing Distortion Product (DP) Waves in a Cochlear Model. AIP Conf Proc. 2011 Nov; 1403(1):557-562. PMID: 25284909.
      View in: PubMed
    36. Verhulst S, Shera CA, Harte JM, Dau T. Can a Static Nonlinearity Account for the Dynamics of Otoacoustic Emission Suppression? AIP Conf Proc. 2011 Nov; 1403(1):257-263. PMID: 25284908.
      View in: PubMed
    37. Joris PX, Bergevin C, Kalluri R, Mc Laughlin M, Michelet P, van der Heijden M, Shera CA. Frequency selectivity in Old-World monkeys corroborates sharp cochlear tuning in humans. Proc Natl Acad Sci U S A. 2011 Oct 18; 108(42):17516-20. PMID: 21987783; PMCID: PMC3198376.
    38. Shera CA, Olson ES, Guinan JJ. On cochlear impedances and the miscomputation of power gain. J Assoc Res Otolaryngol. 2011 Dec; 12(6):671-6. PMID: 21947765; PMCID: PMC3214245.
    39. Sisto R, Moleti A, Botti T, Bertaccini D, Shera CA. Distortion products and backward-traveling waves in nonlinear active models of the cochlea. J Acoust Soc Am. 2011 May; 129(5):3141-52. PMID: 21568417; PMCID: PMC3324258.
    40. Sisto R, Shera CA, Moleti A, Botti T. Forward- and Reverse-Traveling Waves in DP Phenomenology: Does Inverted Direction of Wave Propagation Occur in Classical Models? AIP Conf Proc. 2011; 1403. PMID: 24376285.
      View in: PubMed
    41. Shera CA, Bergevin C, Kalluri R, Laughlin MM, Michelet P, van der Heijden M, Joris PX. Otoacoustic Estimates of Cochlear Tuning: Testing Predictions in Macaque. AIP Conf Proc. 2011; 1403:286-292. PMID: 24701000.
      View in: PubMed
    42. O'Gorman DE, Colburn HS, Shera CA. Auditory sensitivity may require dynamically unstable spike generators: evidence from a model of electrical stimulation. J Acoust Soc Am. 2010 Nov; 128(5):EL300-5. PMID: 21110542; PMCID: PMC2997813.
    43. Shera CA, Guinan JJ, Oxenham AJ. Otoacoustic estimation of cochlear tuning: validation in the chinchilla. J Assoc Res Otolaryngol. 2010 Sep; 11(3):343-65. PMID: 20440634; PMCID: PMC2914235.
    44. Bergevin C, Shera CA. Coherent reflection without traveling waves: on the origin of long-latency otoacoustic emissions in lizards. J Acoust Soc Am. 2010 Apr; 127(4):2398-409. PMID: 20370023; PMCID: PMC2865438.
    45. Voss SE, Adegoke MF, Horton NJ, Sheth KN, Rosand J, Shera CA. Posture systematically alters ear-canal reflectance and DPOAE properties. Hear Res. 2010 May; 263(1-2):43-51. PMID: 20227475; PMCID: PMC3179977.
    46. O'Gorman DE, White JA, Shera CA. Dynamical instability determines the effect of ongoing noise on neural firing. J Assoc Res Otolaryngol. 2009 Jun; 10(2):251-67. PMID: 19308644; PMCID: PMC2674196.
    47. Shera CA, Tubis A, Talmadge CL. Testing coherent reflection in chinchilla: Auditory-nerve responses predict stimulus-frequency emissions. J Acoust Soc Am. 2008 Jul; 124(1):381-95. PMID: 18646984; PMCID: PMC2677332.
    48. Bergevin C, Freeman DM, Saunders JC, Shera CA. Otoacoustic emissions in humans, birds, lizards, and frogs: evidence for multiple generation mechanisms. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2008 Jul; 194(7):665-83. PMID: 18500528; PMCID: PMC2562659.
    49. Sisto R, Moleti A, Shera CA. Cochlear reflectivity in transmission-line models and otoacoustic emission characteristic time delays. J Acoust Soc Am. 2007 Dec; 122(6):3554-61. PMID: 18247763.
      View in: PubMed
    50. Kalluri R, Shera CA. Comparing stimulus-frequency otoacoustic emissions measured by compression, suppression, and spectral smoothing. J Acoust Soc Am. 2007 Dec; 122(6):3562-75. PMID: 18247764.
      View in: PubMed
    51. Shera CA. Laser amplification with a twist: traveling-wave propagation and gain functions from throughout the cochlea. J Acoust Soc Am. 2007 Nov; 122(5):2738-58. PMID: 18189566.
      View in: PubMed
    52. Kalluri R, Shera CA. Near equivalence of human click-evoked and stimulus-frequency otoacoustic emissions. J Acoust Soc Am. 2007 Apr; 121(4):2097-110. PMID: 17471725.
      View in: PubMed
    53. Shera CA, Tubis A, Talmadge CL, de Boer E, Fahey PF, Guinan JJ. Allen-Fahey and related experiments support the predominance of cochlear slow-wave otoacoustic emissions. J Acoust Soc Am. 2007 Mar; 121(3):1564-75. PMID: 17407894.
      View in: PubMed
    54. Shera CA, Guinan JJ. Cochlear traveling-wave amplification, suppression, and beamforming probed using noninvasive calibration of intracochlear distortion sources. J Acoust Soc Am. 2007 Feb; 121(2):1003-16. PMID: 17348523.
      View in: PubMed
    55. de Boer E, Nuttall AL, Shera CA. Wave propagation patterns in a "classical" three-dimensional model of the cochlea. J Acoust Soc Am. 2007 Jan; 121(1):352-62. PMID: 17297790.
      View in: PubMed
    56. Voss SE, Horton NJ, Tabucchi TH, Folowosele FO, Shera CA. Posture-induced changes in distortion-product otoacoustic emissions and the potential for noninvasive monitoring of changes in intracranial pressure. Neurocrit Care. 2006; 4(3):251-7. PMID: 16757834.
      View in: PubMed
    57. Shera CA, Tubis A, Talmadge CL. Coherent reflection in a two-dimensional cochlea: Short-wave versus long-wave scattering in the generation of reflection-source otoacoustic emissions. J Acoust Soc Am. 2005 Jul; 118(1):287-313. PMID: 16119350.
      View in: PubMed
    58. Shera CA, Tubis A, Talmadge CL. Do forward- and backward-traveling waves occur within the cochlea? Countering the critique of Nobili et al. J Assoc Res Otolaryngol. 2004 Dec; 5(4):349-59. PMID: 15675000; PMCID: PMC2504571.
    59. Voss SE, Shera CA. Simultaneous measurement of middle-ear input impedance and forward/reverse transmission in cat. J Acoust Soc Am. 2004 Oct; 116(4 Pt 1):2187-98. PMID: 15532651.
      View in: PubMed
    60. Shera CA. Mechanisms of mammalian otoacoustic emission and their implications for the clinical utility of otoacoustic emissions. Ear Hear. 2004 Apr; 25(2):86-97. PMID: 15064654.
      View in: PubMed
    61. Goodman SS, Withnell RH, Shera CA. The origin of SFOAE microstructure in the guinea pig. Hear Res. 2003 Sep; 183(1-2):7-17. PMID: 13679133.
      View in: PubMed
    62. Oxenham AJ, Shera CA. Estimates of human cochlear tuning at low levels using forward and simultaneous masking. J Assoc Res Otolaryngol. 2003 Dec; 4(4):541-54. PMID: 14716510; PMCID: PMC3202745.
    63. Shera CA. Mammalian spontaneous otoacoustic emissions are amplitude-stabilized cochlear standing waves. J Acoust Soc Am. 2003 Jul; 114(1):244-62. PMID: 12880039.
      View in: PubMed
    64. Shera CA, Guinan JJ. Stimulus-frequency-emission group delay: a test of coherent reflection filtering and a window on cochlear tuning. J Acoust Soc Am. 2003 May; 113(5):2762-72. PMID: 12765394.
      View in: PubMed
    65. Shera CA, Guinan JJ, Oxenham AJ. Revised estimates of human cochlear tuning from otoacoustic and behavioral measurements. Proc Natl Acad Sci U S A. 2002 Mar 05; 99(5):3318-23. PMID: 11867706; PMCID: PMC122516.
    66. Shera KA, Shera CA, McDougall JK. Small tumor virus genomes are integrated near nuclear matrix attachment regions in transformed cells. J Virol. 2001 Dec; 75(24):12339-46. PMID: 11711624; PMCID: PMC116130.
    67. Shera CA. Intensity-invariance of fine time structure in basilar-membrane click responses: implications for cochlear mechanics. J Acoust Soc Am. 2001 Jul; 110(1):332-48. PMID: 11508959.
      View in: PubMed
    68. Shera CA. Frequency glides in click responses of the basilar membrane and auditory nerve: their scaling behavior and origin in traveling-wave dispersion. J Acoust Soc Am. 2001 May; 109(5 Pt 1):2023-34. PMID: 11386555.
      View in: PubMed
    69. Kalluri R, Shera CA. Distortion-product source unmixing: a test of the two-mechanism model for DPOAE generation. J Acoust Soc Am. 2001 Feb; 109(2):622-37. PMID: 11248969.
      View in: PubMed
    70. Shera CA, Talmadge CL, Tubis A. Interrelations among distortion-product phase-gradient delays: their connection to scaling symmetry and its breaking. J Acoust Soc Am. 2000 Dec; 108(6):2933-48. PMID: 11144585.
      View in: PubMed
    71. Voss SE, Rosowski JJ, Merchant SN, Thornton AR, Shera CA, Peake WT. Middle ear pathology can affect the ear-canal sound pressure generated by audiologic earphones. Ear Hear. 2000 Aug; 21(4):265-74. PMID: 10981602.
      View in: PubMed
    72. Voss SE, Rosowski JJ, Shera CA, Peake WT. Acoustic mechanisms that determine the ear-canal sound pressures generated by earphones. J Acoust Soc Am. 2000 Mar; 107(3):1548-65. PMID: 10738809.
      View in: PubMed
    73. Shera CA, Guinan JJ. Evoked otoacoustic emissions arise by two fundamentally different mechanisms: a taxonomy for mammalian OAEs. J Acoust Soc Am. 1999 Feb; 105(2 Pt 1):782-98. PMID: 9972564.
      View in: PubMed
    74. Zweig G, Shera CA. The origin of periodicity in the spectrum of evoked otoacoustic emissions. J Acoust Soc Am. 1995 Oct; 98(4):2018-47. PMID: 7593924.
      View in: PubMed
    75. Shera CA, Zweig G. Noninvasive measurement of the cochlear traveling-wave ratio. J Acoust Soc Am. 1993 Jun; 93(6):3333-52. PMID: 8326061.
      View in: PubMed
    76. Shera CA, Zweig G. Middle-ear phenomenology: the view from the three windows. J Acoust Soc Am. 1992 Sep; 92(3):1356-70. PMID: 1401522.
      View in: PubMed
    77. Shera CA, Zweig G. An empirical bound on the compressibility of the cochlea. J Acoust Soc Am. 1992 Sep; 92(3):1382-8. PMID: 1401524.
      View in: PubMed
    78. Shera CA, Zweig G. Analyzing reverse middle-ear transmission: noninvasive Gedankenexperiments. J Acoust Soc Am. 1992 Sep; 92(3):1371-81. PMID: 1401523.
      View in: PubMed
    79. Shera CA, Zweig G. Phenomenological characterization of eardrum transduction. J Acoust Soc Am. 1991 Jul; 90(1):253-62. PMID: 1880296.
      View in: PubMed
    80. Shera CA, Zweig G. A symmetry suppresses the cochlear catastrophe. J Acoust Soc Am. 1991 Mar; 89(3):1276-89. PMID: 2030215.
      View in: PubMed
    81. Shera CA, Zweig G. Reflection of retrograde waves within the cochlea and at the stapes. J Acoust Soc Am. 1991 Mar; 89(3):1290-305. PMID: 2030216.
      View in: PubMed
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