Jeffrey Vernon

Professor Sekuler

Sensory Processes

21 November 2000

My Experiences During a Period of Intentionally-Induced Temporary Hearing Loss

As the earplugs sealed into place, one thing became immediately apparent. Something was…off. I couldn't quite put my finger on it. The world seemed…quieter, but it didn't appear to be missing any sounds that I normally took notice of. In fact, it was only now that I could not hear them that I began to notice them! The hum of my hard drive, the sound of wind blowing in through my window--both gone. The earplugs had caused a noticeable conduction loss, reducing the amount of acoustic energy reaching my inner ear's neural receptors. As a result of this diminished level of sound input those noises that are normally audible, but so faint that they merely lie in the background, were completely gone.

Even more pronounced then the sounds that were gone, however, were those that were now there. I could hear my breathing from inside of me. I had never (noticeably) been able to do this before. No doubt this was due to bone conduction, for with the level of sound reaching my ears through normal channels greatly diminished, I was now able to pick up on sounds as faint as the ones that sent very small ripples through my basilar membrane due to minor disturbances in my cochlear fluid caused by reverberations through my skull that were initiated by the motion of my lungs as I inhaled and exhaled. An even more prominent, normally "silent" sound was that of my footsteps. While walking around my suite, I noticed a very low-frequency but high-intensity "thump" every time I took a step. Thanks to bone conduction, it was as if I had a miniature bass drum inside my head, going off every second.

The next thing I did was tell my suitemates about the little experiment I was conducting. I soon realized I should have told them before I had inserted the plugs. Not surprisingly, communication was extremely difficult. I could usually discern their words, but it required a great deal of concentration. The extra attention I needed to divert to this task was probably due to the necessity of aiding my brain in making up for words I may have missed by "filling-in" words within the context of the conversation. I also had to ask them to "speak up", so that the intensity of the sound energy of their speech, that is, the decibel level of their speech, was raised, thus giving my ears more sound energy to capture and, consequently, convert to neural signals. It should come as no surprise, however, that these earplugs had such a deleterious effect on conversation, as they attenuate sound greatest between the frequencies of 125 to 8,000 Hz. Normal human speech covers a range of 200 to 8,000 Hz. This is no coincidence. These earplugs are designed specifically to inhibit the auditory perception of speech! And not merely of one's partners. It was pointed out to me that I was speaking inordinately loud, no doubt in order to hear myself better.

The remainder of my night was spent in my room. I had become frustrated speaking with my suitemates, and I could tell the feeling was mutual. I can definitely see why people with hearing deficits often become socially withdrawn. I was fed-up with conversation, and I had only lost some of my hearing--and only for a few hours! As I watched my clock, waiting for the time when I could remove the plugs, I listened to some music, then watched TV. Both activities were completed successfully and with no loss in understanding. However, in order to accomplish this I had to turn both my stereo and, later, my TV up to near-full volumes--and at that point the volumes merely seemed normal to me. When the deadline finally arrived, I was more than grateful. Immediately upon removing the earplugs, sound came flooding back. My hard drive, the wind. My TV was blaringly loud. I next spoke with my roommates; their speech came in loud and clear. I noticed something else, too. In a mere eight hours I had become so accustomed to a low level of sound that for the first few minutes with the plugs out everything actually sounded a bit…strange. Of particular note was the sound of my voice. Normally, one perceives one's voice as the addition of the sound transmitted through the air and then passing through the pinnas, reaching the ears through that path, and the waves produced by the vibrations of your vocal cords reverberating through your skull and reaching the cochlea by that means (bone conduction). With the earplugs in, the sound able to reach my ears through the first path was greatly reduced, thus emphasizing the auxiliary pathway. During the experiment, I had adapted to this as being the sound of my voice. Once the plugs were removed, however, and I was free to access my chief hearing implement again, it sounded much different--clearer, louder, more resonant.

While definitely an extremely valuable learning experience, teaching us how much we rely on hearing in everyday life (especially during conversation) and demonstrating the effects of hearing loss, thus giving us a glimpse into the perceptual universe of the hearing impaired, this experience was also quite frustrating. But, then again, I think that may have been the point.