A simple digital method is described that can produce an undistorted acoustic sine wave using an amplifier and loudspeaker having considerable intrinsic distortion, a common situation at low frequencies and high power. The method involves, first, using a pure sine wave as the input and measuring the distortion products. An iterative procedure then progressively adds harmonics with appropriate amplitude and phase to cancel any distortion products. The method is illustrated by producing a pure 52 Hz sine wave at 107 dB sound pressure level with harmonic distortion reduced over the audible range to >65 dB below the fundamental.
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April 01 2014
Producing undistorted acoustic sine waves
Henri Boutin, John Smith, Joe Wolfe; Producing undistorted acoustic sine waves. J. Acoust. Soc. Am. 1 April 2014; 135 (4): 1665–1667. https://doi.org/10.1121/1.4868374
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