Superfluids support many different types of sound waves. We investigate the relation between the sound waves in a relativistic and a non-relativistic superfluid by using hydrodynamics to calculate the various sound speeds. Then, using a particular holographic scalar gravity realization of a strongly interacting superfluid, we compute first, second and fourth sound speeds as a function of the te...

The SINE WAVE ORCHESTRA (SWO) is a collaborative sound performance project that has been actively performing for the past several years. The basic idea is that each participant plays a sine wave, and by changing its frequency and volume, creates a collection of sine waves as a collective sound representation. Although all SWO works use the same sound representation (i.e., sine waves), different...

The weakly nonlinear interaction of sound and linearly polarised Alfvén waves propagating in the same direction along an applied magnetic field is studied. It is found that a sound wave is coupled to the Alfvén wave with double period and wavelength when the sound and Alfvén speeds are equal. The Alfvén wave drives the sound wave through the ponderomotive force, while the sound wave returns ene...

By radiating bifrequency primary waves from two ultrasonic emitters with changing the phases of the primary waves, we can obtain the sound fields that are different from the usual inphase excitation. Especially, for the excitation of out-phase by 180 degrees the difference frequency wave has the directivity of almost uniformity near the acoustic axis. Additionally, the sound pressure levels of ...