Fig 1. Experimental setup and the sounds used in the experiment.

(A) A full-range speaker was located in a cell culture incubator. The speaker body was tilted to direct the speaker output straight toward the cell culture dish. (B) Shape and averaged spectrum of the sound used in this assay. 440 Hz sine-, triangle-, and square-waves were used as well as white noise, the mixture of all frequencies of sounds. Displacement in 0.01 second (upper panels) and averaged spectrum of the frequency composition up to 8 kHz (lower panels) are shown. 440 Hz positions are indicated by arrowheads.