Meghan's PHY101 Project
Background and Procedure Results References

Cochlear Implants

Background
Cochlear Implants are surgically implanted and excite certain regions of the Basilar Membrane. The location of the stimulation determines the pitch of the sound. Low frequencies excite the apex of the Basilar Membrane, creating a low-pitch sound. Higher frequencies stimulate the basal end of the membrane, creating a high pitch sound. There are different types of Cochlear Implants, and they can contain multiple different wires or channels. These wires will stimulate different regions on the Basilar Membrane, causing patients to hear certain frequencies.

Many people in the hearing world do not understand why it is so hard to adjust to having a Cochlear Implant. Speech often sounds very mechanical with an implant. The purpose of the experiment was to educate the hearing world about what it may sound like to hear using a Cochlear Implant. The experiment will also measure the frequencies at which speech is most easily understood.

Procedure
The participant was informed that they would not be harmed during the experiment and that they could cease participation at any time if they became uncomfortable.
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The participant was shown a list of 200 words, and informed that they would hear 45 of them in a random order.
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participant reading word list

The participant was then played a series of sound files, and was instructed to write do wn the words that they heard. In order for the participant to understand what they would be hearing, a clip from Comma Gets a Cure by Jill McCullough & Barbara Somerville was read and filtered through C-Sound. The clip began without any filter, and was repeated with a ban-pass filter of 500 hz, then 1000hz, 2000hz, and 4,000 hz. The participant was not required to write anything down at this point in the experiment, they were simply instructed to listen.

The word list trials had several different filters. The first set contained 9 words unfiltered, 9 words filtered at 500hz, 9 words filtered at 1000hz, 9 words filtered at 2000hz, and 9 words filtered at 4,000hz. The next set contained combinations of frequencies. The first nine words remained unfiltered, but the following 9 words allowed frequencies of 500 and 1000hz, the next nine allowed frequencies of 500 and 2000hz and the last set allowed frequencies of 500 and 4000 hz. The third and final set of words contained filters of 1000 and 2000, 1000 and 4000, and 2000 and 4000. The following words were recorded:

  • hid

  • feast

  • hunt

  • slip

  • fraud

  • bad

  • pan

  • cleanse

  • crash

  • plush

  • fern

  • pants

  • is

  • rise

  • fuss

  • no

  • such

  • creed

  • deed

  • are

  • smile

  • mange

  • grove

  • there

  • death

  • then

  • rub

  • bask

  • dike

  • pile

  • ford

  • folk

  • strife

  • ride

  • nook

  • bar

  • clove

  • hive

  • heap

  • wheat

  • not

  • toe

  • use

  • pest

  • box

  • cane

  • rag

  • end

  • dish

  • rat

    • The participant wrote down each word understood
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    The results were graphed by percent recognition per frequency.
    See Page 2 for Results.