Acoustic energy
Acoustic energy is a property of a periodic pressure wave, or a single pulse, propagating through an elastic medium.
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[edit] Biological sound
Human beings can usually perceive acoustic energy between the frequenies of 20–20,000 Hz, which is the basis of hearing. Human beings hearing depends on age of the listener : children hear better than adults or old people. Men tend to hear a lower range than women (it would be useful to give reference about it).
[edit] High frequencies
Many animals can hear much higher frequencies than humans. A dog whistle produces sounds up to approximately 22 KHz; humans generally cannot hear the frequencies above 20 KHz, and often substantially below that. A cat can hear frequencies at least as high as can a dog, but simply may not be interested in them.
Bats use even higher frequencies to navigate and avoid collisions. Depending on the species, a bat may be able to use frequencies as high as 100 KHz. [1]
[edit] Low frequencies
Some animals, such as whales and other cetaceans, communicate, or possibly navigate, with infrasound below the lower limit of human hearing. [2] Blue whales, for example, often produce fundamental frequencies in the 10-40 Hz range. High-power acoustic energy generated by humans may have effects on cetaceans.
[edit] Applications of acoustic energy
Within the human hearing range, of course, acoustic energy is the mechanism by which speech and music are produced. There are a wide range of medical applications in which acoustic energy above the human hearing range may be used.
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Sonar relies on the transmission and reflection of acoustic energy through water. Sonar signals tend to be in the higher frequencies, including ultrasound, but long-range sonar may use low frequency or infrasound.
[edit] References
- ↑ Cancel, Juan (1998), Frequency of Bat Sonar, in Elert, Glenn, The Physics Factbook™
- ↑ List of whale songs
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