Modeling DPOAE input/output function compression: comparisons with hearing thresholds.
BACKGROUND
Basilar membrane input/output (I/O) functions in mammalian animal models are characterized by linear and compressed segments when measured near the location corresponding to the characteristic frequency. A method of studying basilar membrane compression indirectly in humans involves measuring distortion-product otoacoustic emission (DPOAE) I/O functions. Previous research has linked compression estimates from behavioral growth-of-masking functions to hearing thresholds.


OBJECTIVE
The aim of this study was to compare compression estimates from DPOAE I/O functions and hearing thresholds at 1 and 2 kHz.


METHODS
A prospective correlational research design was performed. The relationship between DPOAE I/O function compression estimates and hearing thresholds was evaluated with Pearson product-moment correlations.


METHODS
Normal-hearing adults (n = 16) aged 22-42 yr were recruited.


METHODS
DPOAE I/O functions (L₂ = 45-70 dB SPL) and two-interval forced-choice hearing thresholds were measured in normal-hearing adults. A three-segment linear regression model applied to DPOAE I/O functions supplied estimates of compression thresholds, defined as breakpoints between linear and compressed segments and the slopes of the compressed segments. Pearson product-moment correlations between DPOAE compression estimates and hearing thresholds were evaluated.


RESULTS
A high correlation between DPOAE compression thresholds and hearing thresholds was observed at 2 kHz, but not at 1 kHz. Compression slopes also correlated highly with hearing thresholds only at 2 kHz.


CONCLUSIONS
The derivation of cochlear compression estimates from DPOAE I/O functions provides a means to characterize basilar membrane mechanics in humans and elucidates the role of compression in tone detection in the 1-2 kHz frequency range.
Hearing Science Laboratory, School of Communication Sciences and Disorders, University of Memphis, Memphis, TN.
Shaum P
SP
Bhagat
D000328:Adult; D001309:Auditory Threshold / Q000502:physiology*; D001489:Basilar Membrane / Q000502:physiology*; D003051:Cochlea / Q000502:physiology; D006309:Hearing / Q000502:physiology*; D006801:Humans; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology; D010469:Perceptual Distortion / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology; D010897:Pitch Discrimination / Q000502:physiology; D011446:Prospective Studies; D055815:Young Adult