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Fonix FP35 hearing aid test box
I cannot level my FP35, any suggestions?
Yes.
It could be caused by a faulty chamber microphone, however there is also a possible 'user generated cause'. In the default settings {Menu from first screen} there is an option to select a 'reference microphone'. Selecting 'yes', by mistake, on an FP35 which does not have a refeence microphone (most do not) will result in a levelling error. See example default menu screen below- the ref mic choice is at the top reight.
A quick explanation of the settings are:
Print label = off - will stop printing the dotted lines on the right side of a printed which most people do not write on.
Printer = internal - you can use an external printer
Screen mode = light - that's dark writing on a light background, you can select to have a dark background with light writing.
Screen saver = 10 - that's the time before the screen goes dark.
Baudrate - only relevant when connected to a computer.
Aid Group = Adpative - Adaptive is correct for digital aids with WDRC, you can also choose AGC and Linear. This field affects the settling time before recording readings (I think!).
Ref mic = off - few FP35 test boxes have a referemnce microphone.
Distortion = Total - this is the usual choice. A choice of 'off' could be the reason you never see distortion results for a pure tone sweep!
Noise reduction (tone - pure tone) = off, 4x - when noise reduction is turned on eg 4X the test box repeats the measurments and takes an average.
Noise reduction (comp - composite and digital composite/speech) = 4X - as above
Please note that noise reduction is a useful feature but does not really allow you to use the test box in a noisy room. We would advise against using a noise reduction greater than 4X, you can get misleading results.
To store changed settings you need to select the 'Store menu' button (bottom right) and follow instructions.
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