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Titolo:
Distortion product otoacoustic emission and auditory brainstem responses in the echidna (Tachyglossus aculeatus)
Autore:
Mills, DM; Shepherd, K;
Indirizzi:
Univ Washington, Dept Otolaryngol, VM Bloedel Hearing Res Ctr, Seattle, WA98195 USA Univ Washington Seattle WA USA 98195 earing Res Ctr, Seattle, WA98195 USA Univ Washington, Dept Head & Neck Surg, Seattle, WA 98195 USA Univ Washington Seattle WA USA 98195 d & Neck Surg, Seattle, WA 98195 USA Univ Melbourne, Dept Otolaryngol, Melbourne, Vic, Australia Univ Melbourne Melbourne Vic Australia ryngol, Melbourne, Vic, Australia
Titolo Testata:
JARO
fascicolo: 2, volume: 2, anno: 2001,
pagine: 130 - 146
SICI:
1525-3961(200106)2:2<130:DPOEAA>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
OUTER HAIR-CELLS; MARSUPIAL MONODELPHIS-DOMESTICA; SINGLE-OSSICLE EAR; ACOUSTIC DISTORTION; INNER-EAR; COCHLEAR AMPLIFIER; MAMMALIAN COCHLEA; BASILAR-MEMBRANE; MECHANICAL AMPLIFICATION; GENERAL-CHARACTERISTICS;
Keywords:
peripheral auditory system; evolution; cochlear amplifier; mammal; monotreme; DPOAE; ABR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Citazioni:
95
Recensione:
Indirizzi per estratti:
Indirizzo: Mills, DM Univ Washington, Dept Otolaryngol, VM Bloedel Hearing Res Ctr, Box 357923,Seattle, WA 98195 USA Univ Washington Box 357923 Seattle WA USA 98195 le, WA 98195 USA
Citazione:
D.M. Mills e K. Shepherd, "Distortion product otoacoustic emission and auditory brainstem responses in the echidna (Tachyglossus aculeatus)", JARO, 2(2), 2001, pp. 130-146

Abstract

The auditory function of four wild-caught echidnas was measured using distortion product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs). Emission audiograms were constructed by finding the stimulus levels required to produce a criterion emission amplitude at a given stimulusfrequency. For an emission amplitude of -10 dB SPL, the median "best threshold" was 28 dB SPL, and this minimum threshold occurred between 4 and 8 kHz for all animals. The relative effective range of auditory function was defined by the frequencies at which the audiogram was 30 dB above its best threshold. For the emission audiograms, the median lower-frequency limit was 2.3 kHz, the upper limit was 18.4 kHz, and the effective range was 2.7 octaves. The audiogram as measured by ABR was also found to be strongly "U" shaped with similar low- and high-frequency limits, i.e., from 1.0 to 13.9 kHz, with an effective range of 3.1 octaves. These results suggest that the echidna has a behavioral hearing sensitivity comparable to that of typical therian mammals (e.g., rabbits and gerbils) but with a significantly narrowerfrequency range. DPOAE responses were also measured in selected animals asa function of the variation of all four stimulus parameters (frequencies and intensities of both stimulus tones). Overall, the measured emission responses establish that the echidna does have a cochlear amplifier, and that it could be the same type as in therian mammals. The amplification mechanismin the echidna, currently unidentified, clearly operates to frequencies above 20 kHz, higher than the hearing function observed in any birds or reptiles but lower than for typical therian mammals. This raises the possibilitythat at least some aspects of the mammalian cochlear amplifier developed early in evolution, before the divergence of the monotremes (echidna and plat)pus) from the mainstream therian mammals (marsupials and placentals). In this respect, the presence or absence of outer hair cell electromotility inmonotremes would have important consequences for understanding the function and evolution of the vertebrate inner ear.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 22/02/20 alle ore 17:59:45