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Titolo:
DIRECT EVIDENCE OF CUBIC DIFFERENCE TONE PROPAGATION BY INTRACOCHLEARACOUSTIC PRESSURE MEASUREMENTS IN THE GUINEA-PIG
Autore:
AVAN P; MAGNAN P; SMURZYNSKI J; PROBST R; DANCER A;
Indirizzi:
UNIV AUVERGNE,SCH MED,BIOPHYS LAB CLERMONT FERRA FRANCE FRENCH GERMAN RES ST LOUIS,PHYSIOL GRP ST LOUIS FRANCE UNIV BASEL HOSP,ENT DEPT CH-4031 BASEL SWITZERLAND
Titolo Testata:
European journal of neuroscience
fascicolo: 5, volume: 10, anno: 1998,
pagine: 1764 - 1770
SICI:
0953-816X(1998)10:5<1764:DEOCDT>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
BASILAR-MEMBRANE; OTOACOUSTIC EMISSIONS; COCHLEAR MECHANICS; DISTORTION PRODUCTS; MOSSBAUER TECHNIQUE; SOUND PRESSURE; CAT COCHLEA; RESPONSES; VIBRATION; PHASE;
Keywords:
COCHLEAR DELAYS; COCHLEAR FILTERING; OTOACOUSTIC EMISSIONS; TRAVELING WAVE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
P. Avan et al., "DIRECT EVIDENCE OF CUBIC DIFFERENCE TONE PROPAGATION BY INTRACOCHLEARACOUSTIC PRESSURE MEASUREMENTS IN THE GUINEA-PIG", European journal of neuroscience, 10(5), 1998, pp. 1764-1770

Abstract

The fine tuning mechanisms involved in the normal processing of soundin the cochlea are non-linear, hence combination tones are generated inside the cochlea when a pair of low-level pure tones with neighbouring frequencies f(1) and f(2) is used as a stimulus. Their detection assounds in the ear canal proves that they undergo backward propagationin the cochlea and through the middle ear, and the non-invasive measurement of the combination tone at 2f(1)-f(2), called the cubic difference tone (CDT), has become a routine method of monitoring cochlear function. In order to gain information on the hypothetical places where CDTs are generated, on their intracochlear levels and propagation velocities, direct measurements of CDT pressure waves were carried out in scala vestibuli and tympani of the first and second turn of the guinea-pig cochlea, Cubic difference tones at 2f(1)-f(2) varied from 0.75 to 9 kHz and were measured with a miniature piezoresistive transducer, Its high sensitivity allowed the detection of CDTs whenever their levelsexceeded 5 dB SPL in the ear canal, i.e. 40 dB SPL (re: 20 mu Pa) inside the cochlea. The levels of CDTs were similar in scala vestibuli ofthe first and second turn. Phase comparisons between measurements at 2f(1)-f(2) in the first and second turn allowed determination of the place where the CDT phase was minimum, it provided an estimation of thegeneration site of the CDT, which appeared to be close to the place tuned to f(2) for stimulus levels lower than 70 dB SPL. Forward and backward travel times from one turn to the other were assessed at severalfrequencies, and both values were shorter than 0.2 ms. In contrast, the overall 'round-trip' delay of CDTs, measured in the ear canal, was about five times larger, suggesting that local filtering processes rather than propagation delays account for the overall CDT delay.

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Documento generato il 02/12/20 alle ore 15:24:11