A sound producing device, comprising at least one air pulse generating element (100, 200, 300 or 400), each of the at least one air pulse generating element (100, 200, 300 or 400) comprising: a membrane; a first air chamber, wherein a chamber pressure exists in the first air chamber; and at least one opening; wherein 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, characterised in that 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; and wherein each of the air pulses is in response to one of a plurality of driving signals, and each of the driving signals is converted from an unit driving signal by scaling with a scaling factor and subsequent level shifting; wherein each of the air pulses has a pulse cycle, and each of the pulse cycles has a pulse-generating time segment and a pulse-isolating time segment in sequence; wherein in each of the pulse cycles, the membrane moves from an initial position to a first position in the pulse-generating time segment, and the membrane moves from the first position to a second position in the pulse-isolating time segment, so as to change the chamber pressure in each of the pulse cycles; wherein the scaling factor is a difference between two successive sampled values of the input signal; wherein the pulse-isolating time segment comprises a falling period (Tf) and an isolation period (Ti) after the falling period (Tf), and the membrane moves from the first position toward the second position during the falling period (Tf); wherein during the isolation period (Ti), the membrane stays at the second position; or the membrane moves for being close to the second position before the membrane stays at the second position. at least one air pulse generating element (100, 200, 300 or 400), each of the at least one air pulse generating element (100, 200, 300 or 400) comprising: a membrane; a first air chamber, wherein a chamber pressure exists in the first air chamber; and at least one opening; wherein 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, characterised in that 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; and a membrane; a first air chamber, wherein a chamber pressure exists in the first air chamber; and at least one opening; wherein 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, characterised in that 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; and wherein each of the air pulses is in response to one of a plurality of driving signals, and each of the driving signals is converted from an unit driving signal by scaling with a scaling factor and subsequent level shifting; wherein each of the air pulses has a pulse cycle, and each of the pulse cycles has a pulse-generating time segment and a pulse-isolating time segment in sequence; wherein in each of the pulse cycles, the membrane moves from an initial position to a first position in the pulse-generating time segment, and the membrane moves from the first position to a second position in the pulse-isolating time segment, so as to change the chamber pressure in each of the pulse cycles; wherein the scaling factor is a difference between two successive sampled values of the input signal; wherein the pulse-isolating time segment comprises a falling period (Tf) and an isolation period (Ti) after the falling period (Tf), and the membrane moves from the first position toward the second position during the falling period (Tf); wherein during the isolation period (Ti), the membrane stays at the second position; or the membrane moves for being close to the second position before the membrane stays at the second position. the membrane stays at the second position; or the membrane moves for being close to the second position before the membrane stays at the second position.