Impact of infrasound on the human cochlea.

Low-frequency tones were reported to modulate the amplitude of distortion product otoacoustic emissions (DPOAEs) indicating periodic changes of the operating point of the cochlear amplifier. The present study investigates potential differences between infrasound and low-frequency sounds in their ability to modulate human DPOAEs. DPOAEs were recorded in 12 normally hearing subjects in the presence of a biasing tone with f(B)=6Hz and a level L(B)=130dB SPL.

Low-frequency characteristics of human and guinea pig cochleae.

Previous physiological studies investigating the transfer of low-frequency sound into the cochlea have been invasive. Predictions about the human cochlea are based on anatomical similarities with animal cochleae but no direct comparison has been possible. This paper presents a noninvasive method of observing low frequency cochlear vibration using distortion product otoacoustic emissions (DPOAE) modulated by low-frequency tones.

[Diagnosis of endolymphatic hydrops using low frequency modulated distortion product otoacoustic emissions].

Background: The low frequency modulation of distortion product otoacoustic emissions (DPOAEs) is an objective audiometric method that appears to be a useful tool for the diagnosis of endolymphatic hydrops (EH), e.g. in patients with Menière's disease, or in those who present only some of the symptoms of the disease.

[Aural fullness and endolymphatic hydrops].

Background: Low-frequency modulated DPOAEs were registrated to investigate whether the subjective symptom of aural fullness can indicate an endolymphatic hydrops.

Method: The cochlear partition is periodically moved towards scala vestibuli and scala tympani by a low-frequency suppressor tone. The level of simultaneously registrated DPOAEs is modulated depending on the phase of the suppressor.

[Objective test of smell with cognitive potentials].

Background: An objective smelling test is indicated for a reliable assessment of olfactory disorders. Usually olfactory evoked potentials (OEP) are registered. But the technique of this measurement is complicated and the generation of the OEP depends on the respiration of the subject.