US Patent 11172310 Sound producing device

A sound producing device includes at least one air pulse generating element. Each of the at least one air pulse generating element includes a membrane, a first air chamber and at least one opening, wherein a chamber pressure exists in the first air chamber. The membrane is actuated to change the chamber pressure of the first air chamber to generate a plurality of air pulses, the air pulses are propagated through the at least one opening, the air pulses produce a non-zero offset in terms of sound pressure level, and the non-zero offset is a deviation from a pressure value of an ambient pressure outside the sound producing device.