Thesis Title

Order Effects And Number Of Tone Pairs During Simultaneous Distortion Product Otoacoustic Emissions


Erin Anderson

Date of Graduation

Spring 2002


Master of Science in Communication Sciences and Disorders


Communication Sciences and Disorders

Committee Chair

Thomas Franklin

Subject Categories

Communication Sciences and Disorders


The distortion product otoacoustic emission (DPOAE) measure has become a standard diagnostic tool in most clinical settings. It can be used either as a screening device or for diagnostic procedures. Most diagnostic DPOAEs can be administered in a few minutes on a cooperative patients. Unfortunately, there are circumstances in which test time may be a factor (i.e., children). Traditionally, the DPOAE has been recorded utilizing primary tone pairs (2F₁-F₂) presented in a sequential manner. Instrumentation now allows multiple primary tone pairs to be presented simultaneously. This could possibly reduce acquisition time for the diagnostic DPOAE. The effects of order and number of simultaneously presented distortion product otoacoustic emissions were examined in subjects with normal hearing (92 ears). DPOAEs were measured sequentially and simultaneously. Frequency pairs (F₁-F₂) were plotted by F₂ on the X-axis DP audiogram at 625 Hz, 1250 Hz, 2500 Hz, and 5000 Hz. The levels of the tone pairs, L₁ and L₂ were 65 dB SPL and 55 dB SPL respectively. Various orders and combinations (10 total) of the four primary tone pairs were presented in the simultaneously condition. The results of the DPOAE amplitudes and noise-floors for each frequency tone pair were analyzed. ANOVA revealed significant differences (p<.01) in DPOAE amplitudes, and noise-floor measures for all combinations. Post-hoc analyis (Bonferroni) was utilized and identified significant differences (p<0.5) for unplanned pairwise multiple comparisions. The results suggest that caution must be used when administering simultaneous multiple tone pair DPOAE presentations. The differences in DPOAE amplitude and noise-floor may possibly be caused by cochlear non-linearities, multiple combinations of non-primary DPOAEs being measured, and/or recording artifacts made by the GSI DPOAE equipments.


© Erin Anderson