Compound Action Potential (AP) Tuning in Man and Guinea Pig: Effect of Probe Tone Level and Hearing Loss
Several studies have indicated the influence of pathology on AP tuning. In animal studies Harris (1979, chinchilla) showed that APTCs usually are broader than single fibre tuning curves at the same characteristic frequency. This was also shown by van Heusden and Smoorenburg (1981, cat). Furthermore, they concluded that after noise trauma the APTC broadens and that the use of a higher probe tone level was only partially responsible for this widening. Gorga and Abbas (1981, cat) observed that sharpness of APTCs, expressed in QlOdB, was unaffected by acoustic trauma or probe level, while the low-frequency tail could become relatively hypersensitive. Shepard and Abbas (1983, cat) correlated APTC findings to histological data from acoustically traumatized ears. They concluded that traumatized ears had a decreased sharpness of tuning and a less sensitive tip and tail region. Also, normal tuning could sometimes go along with hair cell damage. Inner hair cell damage affected the tail position, outer hair cell damage the tip region.
KeywordsHearing Loss Tuning Curve Frequency Selectivity Tone Level Endolymphatic Hydrops
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- Harrison, R.V., Aran, J.M. and Erre, J.P. (1981). AP tuning curves from normal and pathological human and guinea pig, J. Acoust. Soc. Am., 69, 1374–1385.Google Scholar
- Heusden, E. van and Smoorenburg, G.F. (1981). Eight-nerve action-potential tuning curves in cats before and after inducement of an acute noise trauma, Hear. Res. 5, 25–48.Google Scholar
- Kimura, R.S. (1967). Experimental blockage of the endolymphatic duct and its effect on the inner ear of the guinea pig, Annals ORL, 76, 664–687.Google Scholar
- Prijs, V.F. and Harrison, R.V. (1984). Eighth nerve responses in guinea pigs with long term endolymphatic hydrops, Revue Lar., 229–235.Google Scholar
- Shepard, N.T. and Abbas, P.J. (1983). Compound action-potential tuning curves in normal and acoustical traumatized cats, Annals ORL, 92, 496–503.Google Scholar
- Pick, G.F., Evans, E.F. and Wilson, J.P. (1977). Frequency resolution in patients with hearing loss of cochlear origin, in: Psychophysics and Physiology of Hearing, E.F. Evans and J.P. Wilson, eds., Academic, London.Google Scholar
- Evans, E.F. (1977). Frequency selectivity at high signal levels of single units in cochlear nerve and nucleus, in: Psychophysics and Physiology of Hearing, E.F. Evans and J.P. Wilson, eds., pp. 185–192, Academic Press, London.Google Scholar
- Evans, E.F . (1985). Aspects of the neuronal coding of time in the mammalian auditory system relevant to temporal resolution, in: Time Resolution in Auditory Systems, Evans, E.F, ed., pp. 74–95, Springer-Verlag.Google Scholar