Measurement and Application of Equivalent Input Distortion

A new technique for measuring nonlinear distortion in transducers is presented which considers a priori information from transducer modeling. Transducers are single-input, multiple-output (SIMO) systems where the dominant nonlinearities can be concentrated in a single source, adding nonlinear distortion to the input signal. Assessing the distortion at the source results in more meaningful data describing the large-signal behavior of loudspeakers independent of the linear transfer response. Since the distortion source is not accessible for direct measurements, the equivalent input distortions are calculated from the sound pressure output. This technique makes it possible to predict the distortion in the sound field, to investigate the influence of the acoustical environment (room), and to separate noise and other disturbances not generated by the transducer.