Sound generation using photoacoustic effect

It is highly important to generate a point sound source in mid air for several applications such as virtual realty and precise acoustic measurement since most of acoustic theories are based on a point sound source. One possible solution for generating a point sound source in mid air is the photoacoustic effect that generates sounds from the alternate-current components of air expansion due to the heat generated by light absorption of a material when light modulated with acoustic signal is radiated to a material. To apply this method to molecule of gases in mid air, it is possible to generate a point sound source in mid air. Thus, for the first step to realize this possibility, this paper attempt to confirm that it is possible to generate audible sounds using the photoacoustic effect. In particular, this paper describes the sound generation using a charcoal that has high absorptive power and a halogen lamp that can produce high intensity infrared light, which is easier, absorbed by gas molecules than visible light.