Study of SelfFit App for Hearing Loss Diagnostics Based on Threshold Measurements Through In-situ Audiometry and Adjustment of Hearing Device Amplification Parameters in Agreement With Prescriptive Formulas as NAL-NL1,DSL-i/o
Study of SelfFit App for Hearing Loss Diagnostics Based on Threshold Measurements Through In-situ Audiometry and Adjustment of Hearing Device Amplification Parameters in Agreement With Prescriptive Formulas as NAL-NL1,DSL-i/o
The purpose of this clinical study is to validate the comparability of prescription formula fitting of hearing aids based on full diagnostic audiometry and SelfFit interactive fitting of hearing aids based on hearing loss screening (mild to moderate hearing losses) using in-situ audiometry, provided and executed through the mobile medical app.
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.
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