This is documentation for Mathematica 7, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)


AmplitudeModulation[fc, fm, mi, dur]
creates a Sound object that is an amplitude-modulated sinusoid, having carrier and modulating frequencies fc and fm, measured in hertz, a modulation index of mi, and a duration of dur seconds.
AmplitudeModulation[fc, fm, mi, dur, RingModulation->True]
creates a ring-modulated sinusoid
  • To use AmplitudeModulation, you first need to load the Audio Package using Needs["Audio`"].
  • Sounds created using amplitude modulation contain three frequencies: the carrier frequency, and the sum and difference of the carrier and modulating frequencies.
  • The following options can be given:
DisplayFunctionIdentityfunction to apply to sound before returning it
PlayRange{-1, 1}range of sound amplitude levels to include
RingModulationFalsewhether to use ring modulation
SampleDepth8number of bits used to encode sound amplitude
SampleRate8192sampling rate per second
  • The option RingModulation->True specifies that the Sound object created by AmplitudeModulation will contain only two frequencies: the sum and the difference of the carrier and modulating frequencies.
  • The expression used by AmplitudeModulation is given by (m_icos (2 pi f_m t) +1) cos (2 pi f_c t).
  • The expression used by AmplitudeModulation with the option RingModulation->True is given by m_i cos (2 pi f_m t) cos (2 pi f_c t).
  • The depth or intensity of the modulation is controlled by the modulation index mi.
  • The carrier is said to be overmodulated when m_i >1.
  • The best way to understand the effect of mi is to try it out with different values, usually between 0.1 and 2.0.