Noise spectrum and level are changing dynamically in mobile environments. Speaker volume comfortable in quiteconditions becomes too low when the ambient noise level increases significantly. Speaker volume adjusted for goodintelligibility in high ambient noise becomes annoyingly loud in quite. Automatic Volume Control may compensatefor different levels of ambient noise by increasing or decreasing the speaker gain accordingly. However, if the noiseand sound spectra are very different, such simple gain adjustment may not work well. More advanced technologywill dynamically equalize reproduced sound so that it exceeds the noise level by a specified ratio all over thefrequency range. This paper describes principals and practical aspects for Automatic Volume and EqualizationControl in mobile audio and communication devices.
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