| CPC H04R 23/00 (2013.01) [H04R 1/30 (2013.01); H04R 3/04 (2013.01); H04R 7/06 (2013.01); H04R 17/00 (2013.01); H04R 2217/03 (2013.01)] | 27 Claims |

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1. An air-pulse generating device, comprising:
a film structure, comprising a flap pair, wherein the flap pair comprises a first flap and a second flap opposite to each other;
wherein the film structure is driven to form an amplitude-modulated ultrasonic air pressure variation with an ultrasonic carrier frequency;
wherein the flap pair is driven to form a virtual valve or an opening at a rate synchronous with the ultrasonic carrier frequency;
wherein the air-pulse generating device produces a plurality of air pulses according to the amplitude-modulated ultrasonic air pressure variation, and the plurality of air pulses is asymmetric; wherein the first flap is driven by a first demodulation-driving signal and the second flap is driven by a second demodulation-driving signal, such that the flap pair forms the opening;
wherein the virtual valve is closed corresponding to a period within a first transition time of the first demodulation-driving signal and a second transition time of the second demodulation-driving signal.
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