Algorithms Made Easy: Formulas for Hearing Health

Whats an algorithm?
If you don't know what an algorithm is, don't worry. Most people outside of mathematicians, search engine designers and hearing aid designers don't know what an algorithm is either. But, without getting into too much detail, an algorithm is a formula a collection of numbers and odd looking symbols. Want to see one?

Heres an example of a query expansion algorithm courtesy of the UK based Science and Technology Facilities Council - Information Science and Engineering Group:

Zi+1 = Zi.ai+1
ri = 1 + k - k/Zi
(i path steps; relevance constant k; ai is relevance weight of semantic relationship type at ith step; Z is iterative component of the relevance function; ri is relevance at ith step.)

Got that? No? Okay, lets break it down even further.

An algorithm is a formula that tells computers what to do. For example, the search engine, Google, employs a detailed algorithm to assess and index web sites in order of relevance to a users query words. The Google formula includes such factors as newness of content, number of links to and from a web site and how frequently the keywords, entered by the user, appear in the site text. Add up all of these factors (and a few dozen more) and the search engine delivers the most relevant web site links based on the key words used in a Google search.

Thats pretty easy to understand. Algorithms are also used in todays, state-of-the-art hearing aids. You see, contemporary hearing aids are, in fact, miniature computers that are constantly adjusting their settings adjustments made based on the algorithms programmed into the hearing aid.

Recently, the Editor at Audiology Online (www.audiologyonline.com), Dr. Paul Dybala, sat down with Dr. Victor Bray, Vice President and Chief Audiology Officer at SONIC innovations and spoke about algorithms and the use of these mathematical formulas to improve hearing comfort.

Hearing Aid Memory
Things arent the way they used to be. Todays hearing aids are programmed to recognize and memorize certain, common listening environments from loud to soft. Depending on sound levels, background and ambient noise, and the hearing needs of the user, audiologists can program SONIC devices to the most specific needs of virtually every wearer.

During the interview, Dr. Bray described one of SONICs newer offerings Balance. The hearing aid is configured as a one-, two-, three- or four memory hearing aid. Used as a single-memory device, the hearing aid memory is programmed with what SONIC innovations calls its universal program that creates the easiest-to-use hearing aid. Set it. Forget it.

Switching Sound Environments
So lets say that you werent paying too much attention during higher math classes when you were in school. Too many numbers, too many symbols and way too much to remember, and chances are, if you work in an office or factory, you don't use that level of math every day, so hear it is in simple terms.

The programs that run the micro-computers built into quality hearing aids handle many routine chores for the wearer. Move from a soft to a loud environment and sound volume increases correspondingly. Lots of background noise? The algorithm programmed into the computer adjusts the directionality of the microphones.

SONICs DIRECTIONALfocus Algorithm
During an exclusive interview with Audiology Online Editor, Dr. Paul Dybala, SONICs Victor Bray also discussed the basis of the DIRECTIONALfocus algorithm. Simply put, the hearing aid looks for speech input that is in front of the listener and then the hearing aid works to suppress sounds (including speech) coming from other directions. This is especially important when in many high noise situations, such as a restaurant, the noise around you is speech.

Dr. Bray stated, We like adaptive algorithms very much, and we feel weve done an excellent job of getting a single memory hearing aid [equipped with adaptive algorithms]in which the entire internal component (micro-computer) is grounded in ahybrid directionality system, but with a new noise reduction system running on top of that which is not only signal-to-noise ratio dependent, but also sound pressure level dependent.

Thats a lot to absorb, but in summary SONIC, and other manufacturers, all seek ways to improve hearing device performance through the use of multiple algorithms often working in cooperation of each other. Improved sound, improved hearing comfort and adaptable to any listening conditions thats the importance of those mathematical formulas called algorithms.