Solving the Speech Intelligibility in Noise Problem

By Tammara Stender, Au.D

Hearing aid performance in noisy situations is listed as one of the top ten factors in hearing aid user satisfaction.  New innovative approaches to facilitating hearing in noise may increase satisfaction among hearing instrument users. These approaches include strategic microphone placement in non-directional devices and the use of wireless accessories that stream the speaker’s voice directly to the listener’s hearing aids.

Strategic microphone placement as a means to promote better speech intelligibility takes advantage of the natural physical characteristics of the external ear by positioning the microphone in a more optimal location. When the microphone of a hearing instrument is positioned behind the ear, all pinna effects including the ear’s natural directivity and protection from wind noise are obliterated. However, moving the microphone inside the ear canal or even within the bowl of the concha allows for some of these favorable pinna effects to occur, thereby naturally restoring some of the ear’s physiological ability to help the listener discriminate speech from noise. This contribution of outer ear structures has been shown to contribute to greater directivity towards the front than the rear, which translates to better speech understanding in noise.

Wireless streaming can also offer improved performance, especially in the case of a mobile phone, as the user is able to conduct phone conversations at a more favorable signal-to-noise ratio than without the wireless accessory. The Mini Mic, a new wireless accessory coming out this fall, permits the hearing aid user to receive streamed sound directly to the hearing aids from a small microphone that is worn by the speaker. With both of these accessories, the conversation is streamed simultaneously to both hearing aids, providing the additional benefit of binaural listening that is adjusted to the user’s hearing thresholds for each ear.