| CPC H04R 23/00 (2013.01) [H04R 7/04 (2013.01); H04R 2440/07 (2013.01)] | 29 Claims |

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1. An air-pulse generating device, comprising:
a film structure, comprising a flap pair;
wherein the film structure is actuated such that the air-pulse generating device produces a plurality of air pulses at an ultrasonic pulse rate;
wherein a horn-shaped outlet is formed within the air-pulse generating device, and the plurality of air pulses is propagated via the horn-shaped outlet;
wherein the flap pair comprises a first flap and a second flap opposite to each other;
wherein the flap pair is configured to perform a differential mode movement and to form a virtual valve or an opening at an opening rate which is synchronous with the ultrasonic pulse rate;
wherein a slit is formed between the first flap and the second flap, and the opening is formed because of the slit;
wherein a projection of the horn-shaped outlet onto the film structure overlaps with the opening;
wherein the virtual valve is closed within a period corresponding to a first transition time of the first flap and a second transition time of the second flap.
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