Coupler Measurements 77
Confusion with Terminology
With the new testing technology of hearing aid analyzers combined with the
new technology of hearing aids, it’s easy to get terminology confused. Frye
Electronics has always used “noise reduction” to denote the averaging that
the analyzer makes when analyzing data, as described in Section 2.5.1.3 and
Section 2.5.2.3.
Some high-end hearing aids have a function often referred to as “speech
enhancement” or “noise reduction.” This function listens for continuous signals
and lowers the gain of the hearing aid.
Just keep in mind that these are two separate applications of the phrase “noise
reduction” that mean two different things.
3.8.2 Testing Directional Hearing Aids
At the most basic level, the function of directional hearing aids is to amplify
sounds in front of the client while decreasing sounds behind the client, increas-
ing his ability to listen to speech in a noisy environment. Perfect tests of direc-
tionality can only be performed in an anechoic chamber, usually only available
to hearing aid developers and researchers. However, you can use the FP35 ana-
lyzer to perform a basic check of directionality in order to verify that the direc-
tional microphones are functioning properly.
To check directionality:
1. Take out the sound chamber speaker from its compartment.
2. Take out the extension pole located in the right side of the compartment,
and slide the wide end into the hole located on the bottom right corner of
the analyzer.
3. Install the speaker on the extension pole. See Figure 3.8.2A.
Figure 3.8.2A—Speaker on the extension pole
