Study of SelfFit Mobile Medical App for Hearing Loss Diagnostics and Hearing Device Fitting / Fine Tuning

The technology utilized within the mobile medical App is partially described in the US patent application US2011/0002490A1. The app is to be used in combination with a hearing aid to deliver the output and targets accurate individual acoustical amplification for effective compensation of a users hearing loss.

The electronic circuitry incorporating the digital signal processing algorithms - dynamic range compression, noise reduction - is providing the acoustical amplification according to parameters (acoustical gain, compression ratio, time constants) calculated through the App on base of in-situ hearing loss diagnostics (pure tone audiometry, loudness scaling). Within the study, amplification parameters will be transmitted to the prototyped device through a prototyped audio streaming box.

Individual audiogram represents hearing thresholds (softest audible sounds) at different frequencies. At least two test frequencies are used involving one in the lower region of device's bandwidth (such as 750 Hz) and one in the higher region of the device's bandwidth (such as 2 kHz). Hearing thresholds are assessed by presenting pure tones of different known levels (SPL) to the user and the thresholds for each of the test frequencies are determined according to the user response to a verbally formulated question (how many tones did you hear?) and multiple choice answer buttons (0, 1, or 2).

Second hearing loss characteristic obtained by the app. is the personal loudness scaling. By presenting a band-limited noise stimuli and collecting the user response about perceived loudness level Medical Mobile App calculates dynamic range of users hearing at given frequency.

The calculation of optimal amplification parameters is performed by App using a proprietary "fitting formula" derived from scientific data.

Final adjustment of amplification parameters called fine tuning is performed while presenting the user with realistic acoustical environment during operation of the hearing device. Fine tuning relates to slight changes of the parameters initially obtained by the "fitting formula". The acoustical signals are presented using audio streaming through the hearing aid. In particular the presented signals include "speech in quiet" and "speech in background noise". Presented speech signal is composed from two or more sources that are processed with different signal processing parameters. During the presentation of the speech signal App presents the speech source visually as two or more speakers. The user is asked to provide his listening preference by choosing the preferred speaker. The signal processing parameters relating to the preferred sound are used for final adjustment of hearing device.

Inclusion criteria

• Hearing loss at the better ear between 35dB and 50dB (PTA1/2/4)
• Active lifestyle
• No language problems
• No medical contra-indications
• Age: between 18 and 75 years
• About 50% experienced users and 50% new users
• Willing to participate in the trial with one three hour visit to the AMC.

Exclusion criteria

• Conductive hearing loss in the middle ear
• Severe hearing loss