Number of Averages

The number of averages determines how many times the MLS signal is repeated during the measurement. The desired number of coherent averages (pre-averages) can be typed in the edit window or chosen from the list. Up to 256 averages can be done if the sound card resolution is 24 bits, and 65536 averages if it is 16 bits.

The reason for averaging is that it will decrease uncorrelated noise and thus increase the quality of the measurements. For doubling of the number of averages, the signal-to-noise ratio is theoretically increased with 3 dB.

The total measurement time increases when the number of averages increases. Note that if the system you are measuring is somewhat time-variant, a long measurement time can decrease the quality of the measurement. An example of a time-variant system is a concert hall where people are running around. Try to avoid measuring during such situations. In any case, for room acoustical measurements, a measurement time of more than 60 seconds is not recommended. Electrical or mechanical systems are usually very little time-invariant, so for those long measurement times seldom is a problem.