Accelerating observers measure the period of the oscillations taking   place in an acoustic wave (non-longitudinal case)
  We consider a scenario that involves a stationary source of acoustic waves located at the origin of the K(XOY) inertial reference frame and a receiver that performs the hyperbolic motion at a constant altitude. The observer measures the proper reception time of successive wave crests. We investigate its dependence on the propagation speed of the wave and on the altitude at which the motion takes place. 
Stefan Popescu and Bernhard Rothenstein