Abstract: A system for controlling distortion comprising a total harmonic distortion (THD) modeling system configured to apply a chirp signal to a system and to identify one or more frequency bands at which distortion is present, and to apply a ramping signal to identify for each of the one or more frequency bands an input signal level at which distortion is initiated, a signal processing system configured to receive an input signal, to determine whether frequency components are present in the input signal that are associated with the one or more frequency bands at which distortion is present, and to limit the amplitude of the input signal at the one or more frequency bands, such as by applying dynamic range compensation.

Abstract: A system and apparatus for constructing a displacement model across a frequency range for a loudspeaker is disclosed. The resultant displacement model is centered around the distortion point. Once a distortion model is constructed it can be incorporated into an audio driver to prevent distortion by incorporating the model and a distortion compensation unit with a conventional audio driver. Various topologies can be used to incorporate a distortion model and distortion compensation unit into an audio driver. Furthermore, a wide variety of distortion compensation techniques can be employed to avoid distortion in such an audio driver.

Abstract: Peak reduction and power limitations are used to prevent distortion and protect components. In a cellular telephone, peak reduction can be based on battery power level to prevent electrical distortion from saturation. In addition peak reduction can be used to prevent mechanical distortion such as rub and buzz. Dynamic range compression can be used for peak reduction. In another application dynamic range compression can be used to control the power output to protect a speaker from damage. One example of a dynamic range compressor/peak limiter comprises a look-ahead buffer and an analysis engine. For example, the look-ahead buffer holds a window of samples of a signal. The analysis engine selects a gain envelope function on the basis of the samples, for example, by selecting the Pth sample in the buffer whenever that sample exceeds a given threshold.