Effect of Stimulus Parameters, Age and Gender on Cubic Difference Distortion Product Otoacoustic Emission Measurement for Hearing Screening and Diagnosis

Distortion product otoacoustic emissions (DPOAEs) are a series of combination tones generated in the ear when stimulated with two pure tones of frequency f1 and f2 (in audio range). The most prominent distortion product is the cubic difference tone at 2f1-f2. Maximum level of the DPOAE signals are observed when the frequency ratio f2/f1 is chosen to be 1.22. The objective of this study is to determine the DPOAE response characteristics from normal and hearing impaired subjects and to find the influence of stimulus parameters, age and gender on cubic difference DPOAE responses. The DSP platform controls the microphone/speaker system which generates the acoustical stimuli for presentation to the ear canal and collects the acoustic responses recorded in the ear canal. The signal processing problem involves estimation of the weak DPOAE response under two strong stimuli and background noise. A total of 43 DPOAE responses from neonatal to adult subjects (both male and female) are analyzed. The DPOAE data of both adults and children are compared with individual pure tone audiometric data to investigate how DPOAE responses differentiated ears with normal hearing from impaired ears. DPOAE responses are analyzed under different stimulus parameters. Both age and gender difference affects DPOAE response. DPOAE assessment provides detailed frequency specific information on cochlear function. This property of DPOAEs is used for clinical applications to find hearing impairments and hearing screening.