underwater sound reference division ultrasound

The frequency of middle ∼ on a piano is 246 Hz. Below 20 Hz, sounds are referred to as infrasonic, and above 20,000 Hz as ultrasonic. Humans generally hear sound waves whose frequencies are between 20 and 20,000 Hz. To the human ear, an increase in frequency is perceived as a higher pitched sound, while a decrease in frequency is perceived as a lower pitched sound. The basic components of a sound wave are frequency, wavelength and amplitude.įrequency is the number of pressure waves that pass by a reference point per unit time and is measured in Hertz (Hz) or cycles per second. The compressions and decompressions associated with sound waves are detected as changes in pressure by the structures in our ears and most man-made sound receptors such as a hydrophone, or underwater microphone. Sound waves radiate in all directions away from the source like ripples on the surface of a pond. When underwater objects vibrate, they create sound-pressure waves that alternately compress and decompress the water molecules as the sound wave travels through the sea. Ocean acoustics is the study of sound and its behavior in the sea. NOAA Pacific Marine Environmental Laboratory Click image for larger view.Ĭlick image to hear a scale of various frequencies (576 K, QuickTime). In this example of a sound wave, the period of one cycle of this wave is 0.5 seconds, and the frequency of this wave is 2 cycles per second or 2 Hertz (Hz). The basic components of a sound wave are frequency, wavelength and amplitude.

Underwater sound reference division ultrasound