Modulator processing for a parametric speaker system

A method for producing a reduced distortion audio signal for use with a parametric loudspeaker system, comprising the steps of:

• (a) receiving at least one audio signal;
• (b) producing a carrier frequency which is modulated with the at least one audio signal to produce a modulated signal with sideband frequencies;
• (c) compensating for an inherent parametric demodulation distortion in parametric loudspeaker demodulation by modifying the modulated signal with added frequencies substantially only within the modulated signal's bandwidth to closely approximate an ideal modulation envelope;
• wherein step (c) further comprises the steps of:
• comparing the modulated signal with the ideal signal to which parametric demodulation distortion has been applied, to thereby produce an inverted error signal;
• adding the inverted error signal back into the modulated signal to produce a compensated modulated signal which is provided to a transducer for audio reproduction.

A signal processor for a parametric loudspeaker system, comprising:

• at least one carrier frequency generator to produce a carrier frequency;
• a modulator which receives at least one audio signal and modulates the at least one audio signal onto the carrier frequency to produce a modulated signal, wherein the at least one audio signal is converted to sideband frequencies which are divergent from the carrier frequency by the frequency value of the at least one audio signal;
• an error correction compensator coupled to the modulator to compensate for transducer distortion by modifying, substantially only within the modulated signal's bandwidth, the modulated signal to approximate an ideal signal which should be output by the system;
• wherein the error correction compensator adjusts for the transducer distortion by comparing the modulated signal with a reference signal which models parametric demodulation distortion, and thereby generates an inverted error difference to add back into the modulated signal substantially within the modulated signal's bandwidth to correct for distortion.