Otoacoustic emissions and bone conduction

grantor: University of TorontoIn clinical and research applications, distortion product otoacoustic emissions (DPOAEs) are almost exclusively elicited using airborne acoustic stimuli. This work introduces and investigates bone conduction (BC) as an alternative pathway for their stimulation. The BC DPOAE offers the possibility of simplified acoustic probe design, improved discrimination of the emission in the ear canal, and the option of rapid bilateral screening protocols. Subsequently, DPOAEs are themselves employed as a tool in the study of the BC phenomenon. Vibration transducers used to stimulate DPOAEs are calibrated by correlating emissions obtained through air and bone modalities. This technique requires only passive cooperation of the participant and is specific to the individual. It is therefore of value for obtaining objective standards with special populations like children, and in research applications where calibration specific to the individual under study is of interest. With models of the auditory periphery, the DPOAE is further employed to obtain a transfer function description of the BC pathway. Both magnitude and phase information of the DPOAE and its stimuli, are used in conjunction with the model and measured applied force to obtain the non-parametric system description. The measured ear canal sound pressure during BC can be removed from the total response through vector subtraction to obtain the middle and inner ear contributions to the net BC signal. Knowledge of the BC transfer function of the individual is useful for auditory research, and the average normal function is of value in clinical diagnosis and design of assistive devices.Ph.D