Distorsively produced otoacoustic emissions

Distorsively produced otoacoustic emissions . (also distortion products , abbreviation DPOAE , from the Greek otos "ear") are otoacoustic emissions that can be observed on the inner ears of mammals . If an inner ear is stimulated with two sinusoidal sound stimuli , the frequencies of which are in a certain ratio to one another, a third vibration with a different frequency is generated in the inner ear. In everyday life, this form of otoacoustic emissions is often incorrectly referred to as the distortion products of otoacoustic emissions .

Emergence

DPOAE are generated by two simultaneously applied sine tones (f1 and f2). In the nonlinear system of the cochlea it causes distortion (English distortion ) that stand as an amplitude increase in the measured spectrum. The frequency and amplitudes of the distortion products depend on various factors of the stimulation frequencies, which can be described mathematically. In humans, a ratio of has proven to be particularly meaningful. ${\displaystyle f_{dp}=2\cdot f_{1}-f_{2}}$

If you now expose yourself to a sound source that emits two pure tones in a suitable ratio, you can often hear the third tone yourself, i.e. the distortion product of your own ear. This phenomenon is known by musicians as the Tartiniton .

Medical diagnostics

The DPOAE are often issued as an "independent hearing test" because they can scan the cochlea in a frequency-specific manner, but the cut-off of failure is not as sharply defined as in the case of the transitory evoked otoacoustic emissions (TEOAE). DPOAE are still detectable in hearing losses of up to 50 dB (HL). Due to the level-dependent saturation behavior of the OAE, however, the hearing loss can be extrapolated by measuring the growth function.

The DPOAE are therefore not suitable for newborn hearing screening like TEOAE , as they can also be detected in areas of higher inner ear hearing disorders .

See also

• Transient evoked otoacoustic emissions (TEOAE)

literature

• Sebastian Hoth, Katrin Neumann : The OAE manual . 1st edition. Georg Thieme, Stuttgart 2006, ISBN 978-3-13-142561-4 .
• DD Gehr, T. Janssen u. a .: Middle ear and cochlear disorders result in different DPOAE growth behavior: implications for the differentiation of sound conductive and cochlear hearing loss . In: Hearing research . tape 193 , no. 1–2 , 2004, ISSN  0378-5955 , pp. 9-19 , doi : 10.1016 / j.heares.2004.03.018 , PMID 15219315 .

Individual evidence

1. ^ T. Janssen, HP Niedermeyer, W. Arnold: Diagnostics of the cochlear amplifier by means of distortion product otoacoustic emissions. In: ORL. Volume 68, Number 6, 2006, pp. 334-339, ISSN  0301-1569 . doi : 10.1159 / 000095275 . PMID 17065826 . (Review).