Importance

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Abstract

An improved speakerphone for a cellular telephone, portable telephone handset, or the like. In one embodiment, a receiver provides an audio signal, and a first phase-shifter phase-shifts the audio signal by a first phase-shift amount. A second phase-shifter phase-shifts the audio signal by a second phase-shift amount and drives a loudspeaker. A detector generates average and peak values of the first phase-shifted audio signal. A processor sets the first phase-shift amount to each one of a plurality of phase-shift amounts and calculates a corresponding average-to-peak ratio value from the peak and average values. The processor then selects one of the plurality of phase-shift amounts having a corresponding average-to-peak ratio value that meets at least one criteria (e.g., the largest one of the average-to-peak ratio values), and then sets the second phase-shift amount to be the same as the selected phase-shift amount. This enhances the perceived loudness of sound from loudspeaker.

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First Claim