the response of the mammalian peripheral auditory system
Computational models of the auditory-nerve response are
useful tools for understanding the basic physiological processing
underlying auditory perception.
Furthermore, the models may serve as an excellent start point from
which to develop physiologically inspired speech processors for auditory
below). Part of our work focuses on
developing such computational models.
Meddis, R, O'Mard, LPO, and Lopez-Poveda, EA. (2001). "A computational algorithm for computing non-linear auditory frequency
selectivity," J. Acoust. Soc. Am. 109 (6): 2852-2861.
Lopez-Poveda, EA, and Meddis, R. (2001). "A
human nonlinear cochlear filterbank," J. Acoust. Soc. Am. 110 (6):
Sumner, C, Lopez-Poveda, EA, O'Mard, LPO and Meddis,
R. (2002). “A revised model of the inner hair cell and
auditory nerve complex," J. Acoust. Soc. Am. 111 (5): 2178-2188.
E. A., Eustaquio-Martín, A. (2006). "A biophysical
model of the inner hair cell: The contribution of potassium current to
peripheral compression," JARO-J. Assoc. Res. Otolaryngol. 7(3),
Characterizing the response of the human basilar membrane
Applying our computational models to improve auditory prosthesis is
possible only if the models reproduce the main characteristics of human
auditory perception (e.g., frequency selectivity and compression). Part of
our work is dedicated to measure these characteristics, both in normal-hearing
listeners and in listeners with sensorineural hearing loss.
Lopez-Poveda, EA, Plack, CJ, and Meddis, R. (2003).
“Cochlear nonlinearity between 500 and 8000 Hz in normal-hearing
listeners,” J. Acoust. Soc. Am. 113, 951-960.
Plack, CJ, Drga, V, and Lopez-Poveda, EA (2004). "Inferred basilar-membrane
response functions for listeners with mild to moderate sensorineural
hearing loss," J. Acoust. Soc. Am. 115, 1684-1695.
Lopez-Poveda, EA, Plack, CJ, Meddis, R, and Blanco, JL. (2005). "Cochlear
compression between 500 and 8000 Hz in listeners with moderate
sensorineural hearing loss," Hearing Res. 205, 172-183.
The physiological mechanisms for
encoding high-frequency spectral information at high levels
High frequency spectral notches generated by the
filtering action of the pinna are important cues for sound localization.
Phase locking is absent in the response of auditory nerve fibers for
frequencies above approximately 4 kHz. Therefore, high-frequency spectral
notches must be encoded in the rate response of auditory nerve fibers.
However, the rate-response representation of these notches degrades for
high stimulus levels. This has been attributed to two factors: a) basilar-membrane
filters get broader at high levels; and b) most nerve fibers have a narrow
dynamic range.This yields some doubts as to whether spectral notches are
perceived at high levels (e.g. Lopez-Poveda, 1996). The purpose of our
work is to investigate the extent to which this true.
Lopez-Poveda, EA, and Meddis, R.
(1996). "A physical model of sound diffraction and reflections
in the human concha," J. Acoust. Soc. Am. 100, 3248-3259.
Alves-Pinto, A., and Lopez-Poveda, E.A. (2005). "Detection of high-frequency
spectral notches as a function of level," J. Acoust. Soc. Am. 118,
Alves-Pinto, A., Lopez-Poveda, E.A., and Palmer, A. R. (2005). "Auditory
nerve encoding of high-frequency spectral information," in IWINAC
2005, J. Mira and J.R. Alvarez (Eds.), Lecture Notes in Computer
Science 3561, 223-232.
Lopez-Poveda EA, Alves-Pinto A, Palmer AR. (2007) "Psychophysical and physiological assessment of the
representation of high-frecuency spectral notches in the auditory
Hearing: From Sensory Processing to Perception, edited by B Kollmeier, G Klump, V Hohmann, U
Langemann, M Mauermann, S Uppenkamp, J Verhey. Springer-Verlag,
Heidelberg. pp. 51-59.
We design biologically-inspired speech processors based on
our computational models of the human ear.
We aim to apply these speech processors to improve cochlear-implant
speech processors (in collaboration with Blake Wilson), speaker
identification systems (in collaboration with the Crime Scene
Investigation department of the Spanish Guardia Civil), and speech
Wilson BS, Schatzer R, Lopez-Poveda
EA, Sun X, Lawson DT, Wolford RD. (2005). "Two new directions in
speech processor design for cochlear implants," Ear & Hearing,
Wilson BS, Schatzer R, Lopez-Poveda
EA. (2006). "Possibilities for a closer mimicking of normal
auditory functions with cochlear implants," in Cochlear Implants, 2nd
Edition, edited by SB Waltzman and JT Roland, Thieme Medical
Publishers, New York, pp. 48-56.
Wilson BS, Lopez-Poveda
EA, Schatzer R. (2010)."Use of auditory models in developing
coding strategies for cochlear implants," in: Meddis, Lopez-Poveda,
Popper, Fay (eds.) Computer Models of the Auditory System. Springer
Handbook of Auditory Research, Springer, vol. 35, New York, chapter