In this talk, we will explore the concept and physics of Thermphone sound production. Thermophone transducers produce sound by establishing a periodic heat flux into a fluid medium. This heat flux signal engenders a corresponding periodic local pressure rise, in a physically static process.
Pressure field stimulation and sound production via Joule heating has been studied since the late 19th century, though modern capabilities in material science have recently thrust the technology anew into the spotlight due to dramatic improvements in potential device efficiency. Furthermore, it has become apparent that though the physics of sound production and propagation is well understood, the heat transfer mechanisms within the transducers themselves is not well understood. At the temporal and length scales inherent to the operation of these devices, we have uncovered evidence of non-Fourier heat conduction phenomena, such as ballistic and wavelike energy transport processes.
As well as a discussion of the theoretical aspects thermophone sound generation, we demonstrate our research into a novel type of sound cancellation approach that takes advantage of the unique properties of thermophone transducers to perform sound cancellation on the source boundary itself. Finally, we will touch on the implications of this technology for the aerospace industry.
