By Apoorva Murarka
For many people, the sound quality and battery life of their devices are often no more than a second thought. But for hearing aid users, these are pivotal factors in being able to interact with the world around them.
One possible way to update existing technology – which has gone unchanged for decades – is small in size but monumental in impact. Apoorva Murarka, a Ph.D. candidate in electrical engineering at MIT, has developed an award-winning microspeaker to improve the functions of devices that emit sound. Murarka sees hearing aids as one of the most important applications of his new technology.
The Current Problem – Feeling the Heat
Most hearing aids have long used a system of coils and magnets to produce sound within the ear canal. These microspeakers use battery power to operate, and lots of it. Valuable battery life is wasted in the form of heat as an electric current works hard to travel through the coil to eventually help produce sound. The more limited a user’s hearing is, the more the speaker must work to produce sound, and ultimately that much more battery is used up.
As a result, research has shown that many hearing aid users in the United States use about 80 to 120 batteries a year or have to recharge batteries daily. Aside from the anxiety that can accompany the varying dependability of this old technology, the cost of constantly replacing these batteries can quickly add up.
But battery life is not the only factor to consider. Because the coil and magnet system has not been updated in decades, the quality of sound produced by hearing aid speakers (without additional signal processing) has been just as limited. Even small upgrades in sound quality could make a world of difference for users.
The Future Solution – Going Smaller and Smarter
Apoorva Murarka has invented an alternative to the old coil and magnet system, removing those components completely from the picture. In their stead, he has developed an electrostatic transducer that relies on electrostatic force instead of magnetic force to vibrate the sound-producing diaphragm. This way of producing sound wastes much less energy, meaning significantly longer battery life in hearing aids. Apoorva was recently awarded the $15,000 Lemelson-MIT Student Prize for this groundbreaking development.
The biggest difference? Size. You would need to look closely to even see this microspeaker’s membrane – its thickness is about 1/1,000 the width of a human hair.
Additionally, the microspeaker’s ultrathin membrane and micro-structured design enhance the quality of sound reproduced in the ear. Power savings due to the microspeaker’s electrostatic drive can be used to optimize other existing features in hearing aids such as noise filtration, directionality, and wireless streaming. This could pave the way for energy-efficient “smart” hearing aids that improve the quality of life for users significantly.
This invention is being developed further and Apoorva hopes to work with the hard-of-hearing community, relevant organizations and hearing aid companies to understand the needs of users and explore how his invention can be adapted within hearing aids.
You can read more about Apoorva and his invention here.