hearing aid

Styles of hearing aids

Hearing Aid – In 1898, American engineer Miller Reese Hutchinson patented the world’s first battery-powered hearing aid. Today’s models are small, discreet, and extremely sophisticated, catering to millions of people across the world who suffer from hearing loss.

Hearing aids make sounds louder for better hearing. Small microphones collect sounds from the environment. A computer chip converts the incoming sound into digital code. Then it analyzes and adjusts the sound based on the wearer’s hearing loss, listening needs and the level of the sounds nearby. The signals are then converted back into sound waves and delivered through speakers. There are many different styles of hearing aids available.

  • behind-the-ear (BTE) hearing aid hooks over the top of the ear and rests behind the ear. A tube connects the hearing aid to a custom earpiece called an earmold that fits in the ear canal.
  • in-the-canal (ITC) hearing aid is custom molded and fits partly in the ear canal.

hearing loss engineering

  • hearing aids
  • cochiar implants


Audio Illusions (video 3:40) – A set of examples in this short video show how we can hear the same tone or sound in different ways.

  • McGurk effect demonstrates a case where the same sound is perceived as either ‘bar’ or ‘far’ depending on what you’re looking at.
  • tritone paradox, causes people to hear the same set of sounds differently, as either rising or descending tones. This shows how much context and prior experience (some effects even vary based on geography and language from infancy).

Engineering ideas

  • microphone, speaker, digitize, sound waves, noise, amplify, analysis, molding

Do It
Challenges for you to work on…

  • Can You Trust Your Ears? (Audio Illusions) (video 3:40) – Optical illusions are common. Audio illusions are less so. After watching the video and trying the tests, how did you do? Did you “hear” the illusions?
  • Sound – matching puzzle