Amplitude of distortion product otoacoustic emissions in the guinea pig in f(1)- and f(2)-sweep paradigms.
The amplitude versus frequency relations of distortion product otoacoustic emissions (DPOAEs) were studied in the guinea pig, using both the f(1)- and the f(2)-sweep paradigms to vary the primary frequency separation. The amplitude of the DPOAEs 2f(1)-f(2), 3f(1)-2f(2), 4f(1)-3f(2), and 2f(2)-f(1), plotted as a function of DP frequency, exhibited a bandpass structure. The separation of the primaries for which the DPOAE level is maximum is referred to as the optimum ratio f(2)/f(1). For the lower sideband DPOAEs (f(dp)<f(1), f(2)), the optimum ratio varies non-monotonically with the primary frequency region. At an f(2) around 4.4 kHz, the optimum ratio for 2f(1)-f(2) reaches a maximum of about 1.46 while elsewhere it is in the more commonly found 1.2-1.3 range. The width of the amplitude profiles was studied by determining their Q(10 dB). The f(2)-sweep yielded significantly larger Q(10 dB) than f(1)-sweep, for the lower sideband DPOAEs. The amplitude versus frequency functions of the lower sideband DPOAEs approximately line up. Upon closer inspection, however, with f(1)-sweep the 2f(1)-f(2) DPOAE has its maximum at a slightly smaller DP frequency than the higher order DPOAEs. With f(2)-sweep, on the contrary, the 2f(1)-f(2) tends to peak at a higher DP frequency than the other lower sideband distortion products. When the amplitude is considered as a function of the ratio between f(dp) and f(2), the difference between f(1)- and f(2)-sweep with respect to the width and the alignment of the amplitude functions disappears. The amplitude profiles of the lower sideband DPOAEs are a function of the DPOAE frequency f(dp) relative to f(2).
Schneider
S
S
Department of ENT/Audiology, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands. sandra_schnei@hotmail.com
Schoonhoven
R
R
Prijs
V F
VF
D000161:Acoustic Stimulation; D000818:Animals; D001699:Biometry; D005260:Female; D006168:Guinea Pigs; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*