#Technology

Providing some direction … around directional microphone technology in hearing aids

Ever been lost when it comes to directional microphones and in need of easy communication to find some direction? Introducing a document that explains how beamformers work, in a nutshell.

I spent almost a year backpacking through South America and South East Asia in 2009.

What an experience! Total immersion into the sites, the smells and the tastes of many different cultures. Not to mention the beautiful languages, of which I could speak very little. Certainly some help to better understand the local lingo would have proved useful in overcoming what is perhaps the most common communication challenge for people traveling abroad – finding directions to the next cool attraction!

Navigating directionality in microphone technology

As Audiologists, the link between communication ability and directionality is well known, especially when trying to converse in noise. Indeed, difficulties hearing in noise is one of the most common symptoms of hearing loss.¹

And because our natural behavior is to face the person we want to hear, especially in crowds, directional microphones that give a focus to the front and cut noise from behind were developed (see Fig 1).

Fig 1. (A) Schematic circuit diagram illustrating how a fixed directional microphone works to provide differential sensitivity for sounds arriving from different locations. Polar plot showing a cardioid response, giving greatest sensitivity to the front and cutting as much noise as possible from behind.

These have proven successful in improving both the signal-to-noise ratio (SNR) and therefore the ability to hear people in front in noise versus omnidirectional.^2,3 Pioneering systems were fixed and single polar plot. Subsequent technological advances have led to the development of adaptive and multi-channel directional microphone systems.

And innovation in wireless transmission technology has also enabled linking of the 4 microphones across two hearing aids to create a binaural beamformer, and spatial noise cancelling has also been incorporated into some systems.

This has given rise to a host of terminology to describe these different attributes of directional mic behavior that can at times be a little confusing, like me trying to travel around South America on my limited Spanish!

Translating the lingo – beamformers explained

So to help people understand all of this different terminology, I wrote an article titled, Providing some direction – Beamformers explained to help provide some direction. 😊 Happy reading.

References:

NHS. (2018). Symptoms: Hearing loss. Retrieved from https://www.nhs.uk/conditions/hearing-loss/symptoms/.

Gravel, J. S., Fausel, N., Liskow, C., & Chobot, J. (1999) Children’s speech recognition in noise using omni-directional and dual-microphone hearing aid technology. Ear & Hearing, Vol. 20(1), 1-11.

Valente, M., Fabry, D. A. & Potts, L. G. (1995) Recognition of speech in noise with hearing aids using dual microphones. J Am Acad Audio, Vol. 16, 440-449