Click <cr> to enable the dynamic compression ratio measurement.

Click <go> or press the Enter key to start the actual measurement.

Click <go> again or press the ESC key to interrupt or cancel the measurement.

                           Figure 96: Dynamic compression ratio measurement window

Prior to the start of the actual measurement, a prompt for further options will be displayed (Figure 96).

1. Select the type of signal to be used (CHIRP or pure tones) for the measurement.
2. Select an input level and a modulation frequency. Modulation frequency is disabled with pure tones. To measure how a hearing aid will process speech, a modulation frequency of 5 Hz is recommended.
3. Select a level changing speed. Select values that are not too high since the speed will be too fast. Recommended value of 10 dB based on research.
4. Select a lead-time if the hearing aid requires more time to respond to the signal. A lead-time of 15 to 20 seconds is recommended (especially for the CHIRP signal).
5. Click <Start measurement> to start the measurement.
6. The measurement results will appear on the screen when completed. It is possible to show, hide or delete the curves or add a comment.
7. Click <go> again or press the ESC key to interrupt or cancel the measurement.

Note:

The pure tone measurement lasts up to several minutes.

The CHIRP measurement lasts only a few seconds.