The development of an innovative multi-microphone probe and acquisition system for recording otoacoustic emissions {OAEs} with advanced noise cancellation algorithms, increased frequency and intensity ranges and pressurization capabilities is proposed. Two advanced noise cancellation algorithm will be implemented: 1) a multi-reference adaptive noise cancellation (ANC) network and 2) two-dimensional filtering. These algorithms will utilize the independent measurements provided by the multiple microphones in order to reduce noise contaminants. Each microphone or microphone groupings will be connected to individual analog-to-digital (A/D) converters in order to allow for the implementation of the digital signal processing algorithms. The pressurization capabilities of the probe will allow implementation of tympanometry and the acquisition of OAEs while compensating for pressure imbalances between the outer and middle ear. Results from a prototype single microphone long probe are presented demonstrating that the design concept is valid and provides good quality OAE recordings while reducing the undesirable effects of the metal response. The proposed probe will also improve upon the limited dynamic and frequency range of current OAE probes. The probe is expected to be able to provide stimulus levels of up to 90 dB HL and a frequency response of up to 24 kHz. During Phase I, various probes will be constructed and tested under different noise conditions in adult and infant subjects. During Phase II, the pressurization capabilities of the new probe will be further developed and examined. The optimal probe designed will be implemented along with the optimal noise cancellation algorithm and tested in a comprehensive clinical study incorporating the pressurization capabilities of the probe.
