Energy-efficient low-frequency flat acoustic source: analysis, design and experimental validation

There is a need for compact acoustic sources that operate at low frequencies. These acoustic sources can be employed to produce good quality sound in the low frequency range. A problem arising when the acoustic sources operate at low frequencies is that the acoustical power is not always enough to allow for sound to be emitted in the form of propagating waves. As a rule of thumb, in the low frequency range the larger the enclosure volume of acoustic sources, the greater the radiated acoustical power. Therefore, in the applications with limited build space it is difficult to compensate for the sufficient acoustic power of the radiators. A thin sandwich acoustic source with a large surface area and a relatively small thickness that is integrated with an internal cavity can fulfill the need for both large enclosure volume and limited build space. The sandwich structure makes the thin acoustic source light-weight and stiff. Therefore, the resulting acoustic source has a reasonably high fundamental resonance frequency. An inefficient acoustic source consumes extra input electric energy, which causes energy loss and high energy expenses. The existence of an appropriate electrical amplifier in combination with the piezoelectric devices is crucial to achieving an energy-efficient thin acoustic source. An appropriate combination of the actuators and amplifiers is investigated in this research. Due to the limited build space in the low-frequency applications, a need for a compact design of the piezoelectric stack actuators arises. An appropriate auxiliary flexural mechanism is investigated for use as an appropriate driver in the limited space of the thin acoustic source. The resulting acoustic source is thin and energy-efficient and can be used in the low frequency operations. The motivation of the present research is to design a compact energy-efficient actuation mechanism for the thin acoustic source that operates in the low-frequency range.