Suppression of tone burst evoked otoacoustic emissions in relation to frequency separation

• Published in: Hearing research Vol. 148; no. 1; pp. 95 - 106
• Main Authors: Yoshikawa, Hiroshi, Smurzynski, Jacek, Probst, Rudolf
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2000; Elsevier
• Subjects: Acoustic Stimulation - methods; Adolescent; Adult; Biological and medical sciences; Cochlea - physiology; Cochlear mechanic; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Female; Frequency superposition; Fundamental and applied biological sciences. Psychology; Humans; Male; Otoacoustic Emissions, Spontaneous - physiology; Reaction Time - physiology; Suppression; Transiently evoked otoacoustic emission; Vertebrates: nervous system and sense organs; Cochlear mechanic; Transiently evoked otoacoustic emission; Suppression; Frequency superposition; Human; Stimulus frequency; Otoacoustic emission; Mechanical properties; Inner ear; Organ of hearing; Complex tone; Acoustic stimulus; Information processing; Cochlea; Nonlinearity; Superposition
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/S0378-5955(00)00144-1

Tone burst evoked otoacoustic emissions (TBEOAEs) were measured for two tone bursts presented separately and as a two-tone burst complex to examine the linearity of TBEOAE generators for different frequency separations of the stimuli. The stimuli were: (a) tone bursts of 5-ms duration and center frequencies of 1, 1.5, 2 and 3 kHz; (b) complex stimuli with the 1-kHz tone burst combined digitally with each of the other specified tone bursts. Signals were delivered at 70 dB SPL using a non-linear processing method and at 60 dB SPL using a linear method to 21 ears of normally hearing adults. Spectra of TBEOAEs obtained with single-tone bursts were superimposed (composite) and compared to those of the two-tone burst complex. A close correspondence between the composite and complex spectra was present in all ears. However, the components on the higher-frequency slope of the 1-kHz spectral peak were reduced in the complex spectra obtained with a frequency separation of 0.5 kHz when compared to the corresponding composite spectra. The reduction was greater at a stimulus level of 70 dB SPL than with 60 dB SPL. The effect was smaller for a frequency separation of 1 kHz, and almost absent for the tone burst separation of 2 kHz. Thus, suppression leads to weak non-linear frequency superposition for higher-level, closely spaced stimuli.