Intermodulation distortion in audio is usually specified as the root mean square ( RMS ) value of the various sum-and-difference signals as a percentage of the original signal's RMS voltage, although it may be specified in terms of individual component strengths, in decibels, as is common with standard tests include SMPTE standard RP120-1994 or almost but not exactly 3 : 1 for example ).
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Sophisticated pitch generators will also include "'sweep generators "'( a function which varies the output frequency over a range, in order to make frequency-domain measurements ), "'multipitch generators "'( which output several pitches simultaneously, and are used to check for intermodulation distortion and other non-linear effects ), and "'tone bursts "'( used to measure response to transients ).
