Introduction

The invention, in collaboration with INAIL, consists of an innovative method, and a dedicated apparatus, for the measurement of otoacoustic emissions (OAE). By measuring not only the pressure (as in conventional instruments) but also the speed of the acoustic stimulus field and OAE response, a calibration independent of the insertion depth of the probe in the ear canal is obtained, thus improving the reproducibility of this sensitive diagnostic function of the auditory function.

Technical features

The OAE measuring device uses two miniaturized Etymotic ER-2 speakers and an intense Microflown pu probe, assembled in a cavity connected acoustically to the ear canal. The acoustic signals associated with stimuli and waves are measured by the intensity probe both in pressure and in speed. The stimuli are calibrated by equalizing the active intensity (energy transmitted to the middle ear) while the response is converted into the intensity emitted by the eardrum, using a suitable combination of intensity magnitudes. The stability of the calibration and the reproducibility of the OAE measurement are significantly improved and no longer depend, unlike conventional instruments, either on the insertion depth of the probe or on the shape and acoustic impedance of the patient’s ear canal.

Possible Applications

• Clinical audiology diagnostics;
• Estimate of the sensitivity of hearing as a function of frequency;
• Estimate of the frequency resolution of the auditory system;
• Monitoring subjects professionally exposed to noise or other ototoxic agents;
• Neurological diagnostics.

Advantages

• Objective non-invasive and fast (2-3 minutes) test of auditory function;
• Compared to conventional techniques: Calibration of active intensity improves test-retest reproducibility;
• The OAE measured level of the waves is stable, regardless of the probe insertion depth.