Your Audiology Tutorial: Intro

So by now you've probably figured out I'm an audiologist. Someone who performs diagnostic tests for and treats hearing and balance disorders. Many people have not even heard of such a career. If they have, they'll immediately think of hearing aids. Yes, that is one tool for aural rehabilitation, but certainly not the only one. But I'm getting ahead of myself.

Since I am fond of producing series for my blog, it seemed logical that I would start another based on my career. Audiology is a fascinating, diverse discipline that sees constant development and refinement of accepted ideas. Research into many facets of the workings of the auditory pathway-from outer ear to corpus callosum and auditoy cortex-continues to reveal how much we don't fully understand. I am frequently overwhelmed by the amount of new information-new clinical trials, new technology, new strategies. I subscribe to a few peer reviewed journals and find that there are just not enough hours in a week to thoroughly read through them and still have what ressembles a social life. At the very least, I continue to amass an impressive storehouse of info. for my library. I will soon need a new bookcase! Lately, I've been meticulously indexing my old notebooks, making it is efficient as humanly possible should I need to access something quickly.

Each entry in this series will focus on a specific topic, without (hopefully) being too dry. This series will not follow an elementary to more advanced path in any linear fashion. Some posts will deal with straightforward concepts, others will be more complex. It will really depend on what I feel like posting at that time.

Let's get started! For this initial study, we'll start with something most people have at least heard of. Here's an overview as to how noise-cancelling headphones work.

When outside sound hits the headphones’ built-in microphones, an analyzation of the shape of the sound wave is made, with an immediate resulting mirror image of that wave. Milliseconds later, the colliding waves cancel each other out, diminishing what you hear. You may refer to this as "phase-cancellation." As we'll learn later, hearing aid feedback is regulated in much the same manner.

Noise cancelling headphones work best on low frequencies, as wavelengths are longer, giving the headphones more time to negate noise before it enters the ears. An example of low frequency noise with which you might be familiar (especially if you've ever lived in an apartment building), are bass-heavy musical signals. When your neighbor is cranking his or her dancefloor set, you will discern the bass reverberation much more than the higher frequency (treble) components of that music. This is because the lower frequency bass waves are much longer and fewer in number. Higher pitched waves are shorter and tend to reflect off of surfaces with greater ease. You may have also experienced the sort of bass you can "feel". You could call that vibrotactile, but we'll talk abou that in more detail at a later date.

Therefore, noise cancellation headphones are best for jet engine noise, the din of unwanted conversation, the hum of machinery. Try them sometime. You will be delighted to find that that conversational speech will be preserved to good effect while the "junk noise" will be eradicated.