| During the low-pressure phase of each sound wave, bubbles expanded rapidly. |
| We hear different sounds because of variations in the sound wave frequency. |
| And instead of the stylus making a groove that varied in depth, the stylus moved laterally, zigzagging with changes in the sound wave. |
| This phenomenon involves the bending of a sound wave owing to changes in the wave's speed. |
| The bubbles grow in size until they are collapsed rapidly by the compression region of the sound wave. |
| To take the simplest example, consider a sound wave hitting the device directly from above. |
