PP439 - Verification of Smart Glasses as an Assistive Listening Device Using Real Ear Measurements

Abstract: Hearing assistive technology systems (HATS) can enhance the lives of users and increase accessibility. Although the popularity of eyeglass hearing aids diminished in the 1960’s, the value of communication assistance in eyewear has recently re-emerged. ALD glasses may be classified in two ways: text glasses (those that transcribe) and audio glasses (those that amplify through built-in hearing aids). The electroacoustic evaluation of HATS was addressed in ANSI S3.47 but there is no guidance for the evaluation of audio glasses. Therefore, verification was conducted to examine gain and directionality using real-ear measures and Knowles Electronic Manikin for Acoustic Research.

Summary: Purpose

One model of audio glasses was tested in two conditions with the aim of assessing the device’s capabilities. Real-ear measurements were completed on KEMAR via an Audioscan Verifit 2 in order to verify gain adjustments and directionality features.

Methods

Real ear output was first examined across all volume levels on each four hearing loss (HL) configuration presets provided in the smartphone app. Each preset aligned with a specific configuration of hearing loss, A - flat, slight HL, B - sloping, slight HL, C - a sloping, moderate HL, and D - a flat, moderate HL. Real ear measures were conducted in his right ear following typical clinical protocols while KEMAR wore the audio glasses. Output was determined using both female speech (the carrot passage) at 65dB SPL and MPO testing (sweep pure-tone) at 85dB SPL.

The second test was focused on the audio glasses directionality capabilities. The audio glasses used for this study includes a frontal-focused mode, where amplification is focused stimuli in front of the listener. The output was measured to determine how much amplification occurred when used in the frontal focus mode with KEMAR facing the stimulus versus when the he was turned at four azimuths.

KEMAR was set up the same as before with output was measured in his right ear when the audio glasses were set to the lowest and highest volume levels of preset D when positioned at 0, 90, 180, and 270 degrees azimuth.

Results

For the first measurement set across the four configurations of hearing loss, the resulting pure tone average output at frequencies .5, 1, and 2kHz showed an increase from the open-ear measurement of KEMAR that ranged 4 to 7 dB. The highest output (94dB SPL) occurred when the audio glasses setting was at preset D and at the highest volume level.

For the directionality effects, when the hearing aid output was compared across each azimuth, it was discovered that the highest output occurred, as expected, at 0 degrees azimuth when the device was set to its highest volume level. In this position, there was an increase of 8 dB SPL in the pure-tone average output when amplification was introduced when compared to baseline testing without the device at the same azimuth. The hearing aids showed an increase output relative to no glasses of 3, 4, 7 dB SPL when placed at 90, 180 and 270 degrees azimuth, respectively.

Conclusions

Based on these results, it can be determined that the method used to measure the glasses specifications was effective in identifying overall increased levels of output. As innovative technology such as the audio glasses become accessible to the public, it is vital that audiologists evaluate the effectiveness of these devices. Given that there is no coupler for the open fitting of such audio glasses, it is necessary for audiologists to use alternative ways to test device output such as real ear measures.