CancerTreatmentBooks.com
Information About Cancer and Cancer Treatment

Sound

Sound is defined as mechanical compression or longitudinal waves that
propagate through a medium (solid, liquid or gas). Most sounds are
combinations of signals, but a theoretical pure sound can be described as
having a given speed of oscillation or frequency measured in hertz (Hz) and
amplitude or energy with measures such as decibel level. The range of sound
audible to the human ear falls roughly between 20 Hz and 20 kHz at typical
amplitudes with wide variations in response curves. Above and below this
range are ultrasound and infrasound, respectively.

Humans and several animals perceive sounds with the sense of hearing with
their ears, but low frequency sounds can also be felt by other parts of the
body. Sounds are used in several ways, most notably for communication
through speech or, for example, music. Sound perception can also be used for
acquiring information about the surrounding environment in properties such
as spatial characterics and presence of other animals or objects. For
example, bats use one sort of echo-location for flying. Ships and submarines
use sonar. Humans acquire and use spatial information perceived in sounds.

The perceived "amount" of sound (energy of pressure wave) is defined as
loudness and measured in sones. The human ear is most sensitive to sound in
the middle of the audible frequency range. The amplitude of a sound wave is
measured in pascals, and the intensity of a sound is measured in decibels
relative to a stated scale.

Scientific studies of sound are generally classified under the field of
acoustics. Perception of sounds, i.e. hearing, are studied in
psychoacoustics, which also implies the close relation between perception
and psychology. Modelling the sounds that can be heard (and leaving out the
inaudible sounds) is discussed in the psychoacoustic model. Further, the
class of techniques and methods involving sound processing are usually
called audio signal processing methods.

The hearing range varies between different animals: Bats have an unsually
large one, while frogs have a narrow one. Typical frequencies (in hertz) are
listed below:

   * Bat: 100 - 100,000 Hz
   * Dog: 10 - 35,000 Hz
   * Elephant: 1 - 20,000 Hz
   * Frog: 100 - 2,500 Hz
   * Human: 20 - 20,000 Hz

Other meanings of the word "sound"

   * A sound is a body of water, such as Puget Sound.
   * To sound is to measure the depth of water.
   * urethral sounds are medical instruments used for dilating the urinary tract

Cancer - List of Famous Cancer Patients - Medical Topics - Medical_Terms - Medicine - Alternative Therapies -