Calibration - General

Verification of Calibration:

To ensure a secure and constant operation it is necessary that the ACAM system is calibrated frequently. Depending on the intensity of use the calibration should be done weekly to monthly.

You can easily check if a calibration of the device is necessary by doing the following:

Place the coupler and the measuring microphone in the white circle of the Test Box (remove the coupler first) and then perform a normal measurement (for example with a CHIRP signal). The resulting curve should be a flat line with a variance of less than +/- 2 dB from the presetted input level. If the variance is larger, the system must be calibrated in order to deliver correct measurement results.

The verification of the in situ calibration can be made by doing the following:

Place the in situ probe in calibration position (see also chapter: Calibration - In Situ in the same distance from the loudspeaker, as your customer will be later on. Perform a measurement with an input level of at least 70 dB, to be sure no disturbing noise falsifies the measurement. Here too, the result should be a flat curve with a variance of less than +/- 4 dB from the presetted input level.

If after a calibration still no flat curve appears, a microphone is probably damaged. In this case please contact our Support-Center.

Fig.: Status bar during measurement.

During the measurement both microphone levels are displayed in the footer. These levels should correspond with the presetted input level. If one or both of the levels are lower than the input level, one or both microphones may be damaged.

Fig.: Measurement without hearing aid

The curve shows a correct calibration. It is indicated by the flat line and the summation level (small line at the side of the graph) with variance within tolerance limits of +/- 3 dB.