11/21/00

NPSY 12 A

Effects of Impaired Hearing

In order to experience the effects of impaired hearing on perception and to regain my appreciation for the sense of hearing, I conducted an experiment, which impaired my hearing for consecutive eight hours. This was simply done by placing two disposable hearing protectors inside my ears. This procedure simulated conduction-hearing loss by temporarily shifting my hearing threshold. The earplugs increased my hearing threshold by 25 to 45 dB, depending on the frequency of the sound. This shift caused an overall reduction in sensitivity to sounds of all frequencies.

Upon placing the earplugs into my ears, my first observation was that all of the noises around me seemed to either quiet down or completely disappear. What surprised me the most, however, was the fact that my hearing was significantly more sensitive to the sounds coming from within my body. I could hear every breath I took, the movement of my jaw, and the vibrations of every single step I took, seemed to make their way up to my eardrum. The sounds coming from within my body overshadowed everything else that was going on around me. At one point, while I was having lunch with a friend, I could not understand what he was saying to me. Thus, I had to stop chewing my food and keep still every time I wanted to listen to what my fiend had to say.

The reason for my high sensitivity to the noises coming from within me is bone conduction. All of the vibrations caused by my breathing, walking and eating, were transferred through bone to my skull. Since the cochlea is formed within the bone of the skull, all of these vibrations were able to reach the cochlea, and produce sound. Wearing the earplugs did not have any effect on the intensity of the sounds produced by these vibrations. However, since the earplugs attenuated all the sounds around me, the sounds that were caused by bone conduction seemed to be intensified. This phenomenon also caused a problem with my speech. Since the sound of my speech is transmitted through bone conduction, it seemed to be significantly louder then the sound of other people talking. As a result, I did not have a basis on which to judge the loudness of my speech. Thus, I didn’t know if I was talking too loud, or too quietly.

After placing the ear plugs in my ears, I also seemed to experience a high-pitched ringing in my ears. This ringing could have been caused by sounds emitted by my cochlea. The cochlea is capable of generating sound and transmitting it back into the outer ear. These sound waves, would have struck the earplugs inside my ears, forming an echo. The echo would then stimulate my eardrum, causing me to hear the high-pitched sound. After a few hours of wearing the earplugs, it seemed that I adapted to the ringing, and I was not able to detect it anymore.