Test Box – Sound Design
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Click <sound design> to open measuring and evaluation procedures, which measure hearing aids under worn conditions. This will allow the user to compare different hearing aids and determine any errors.


Sound design offers various measurement possibilities. In this section, background information and practical examples are provided regarding sound design.


Click <go> to open the following selection window:

Figure 97: Selection window for sound design measurement.

  1. Select from the following measurement signals:
  • CHIRP
  • Noise
  • Babble of voices
  • Speech
  • ICRA
  • Various pure-tones
  • External signal (play wave file)


  1. Select a measurement time in the 1st measurement field. Adjust the measurment time required (typically 2000-4000 ms).


  1. Select the level of the measurement.


  1. Select an amplitude modulation for the signal (if necessary).


More information regarding the measurement field:

To change the level during the measurement, adjust this setting using measurement – 2nd measurement. The 2nd measurement is grouped to the 1st measurement resulting in a total measurement time: total measurement time = 1st measurement + 2nd measurement.


More information regarding additional signals:

It is possible to add a second signal to the measurement to the test in order to investigate other effects of the hearing aid. Select an appropriate measuring range. If the signal overshoots at the measuring microphone during a measure, the message in Figure 98 will appear. 


Figure 98: Message

Click <yes> to use the measurement.


Click <no> to reject the measurement.

If in doubt, repeat the measurement a higher measuring range.


Click <Start> to start the measurement after the selecting the measurement options. The measurement will complete and stored in the computer.


Various evaluation procedures can be applied to the stored measurement data.


Spectral Compensation:

Enable the option spectral compensation to calculate the performing curve and extracts it from measuring microphone data. As a result, the data corresponds to those of the input signal. The only differences are the changes performed by the hearing aid.


Figure 99: spectral compensation

Select the procedure on the lower right edge of the screen. The evaluation procedures may take several minutes.

Figure 100: differential display

The differential display of the data shows the differences between the measuring microphone and the reference microphone. The differences between both channels are displayed (Figure 100).






Digital hearing aids have a processing time, which may have been measured. When the processing time is known, it is possible to move the measuring microphone and the reference microphone "against each other.” This option is especially important when applying the differential output. The offset may be high.

Figure 101: offset