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Sound
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This article is about audible acoustic waves. For other uses, see Sound (disambiguation).
A drum produces sound via a vibrating membrane.
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid,
or gas, composed of frequencies within the range of hearing.[1] Sound also travels through
plasma.
Contents
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1 Propagation of sound
2 Perception of sound
3 Physics of sound
o 3.1 Longitudinal and transverse waves
o 3.2 Sound wave properties and characteristics
o 3.3 Speed of sound
o 3.4 Acoustics
o 3.5 Noise
4 Sound pressure level
5 Equipment for dealing with sound
6 Sound measurement
7 See also
8 References
9 External links
Propagation of sound
Sound is a sequence of waves of pressure that propagates through compressible media such as air
or water. (Sound can propagate through solids as well, but there are additional modes of
propagation). Sound that is perceptible by humans has frequencies from about 20 Hz to 20,000
Hz. In air at standard temperature and pressure, the corresponding wavelengths of sound waves
range from 17 m to 17 mm. During propagation, waves can be reflected, refracted, or attenuated
by the medium.[2]
The behavior of sound propagation is generally affected by three things:
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A relationship between density and pressure. This relationship, affected by temperature,
determines the speed of sound within the medium.
The propagation is also affected by the motion of the medium itself. For example, sound
moving through wind. Independent of the motion of sound through the medium, if the
medium is moving, the sound is further transported.
The viscosity of the medium also affects the motion of sound waves. It determines the
rate at which sound is attenuated. For many media, such as air or water, attenuation due
to viscosity is negligible.
When sound is moving through a medium that does not have constant physical properties, it may
be refracted (either dispersed or focused).[2]
Perception of sound
Human ear
The perception of sound in any organism is limited to a certain range of frequencies. For
humans, hearing is normally limited to frequencies between about 20 Hz and 20,000 Hz (20
kHz)[3], although these limits are not definite. The upper limit generally decreases with age.
Other species have a different range of hearing. For example, dogs can perceive vibrations higher
than 20 kHz, but are deaf to anything below 40 Hz. As a signal perceived by one of the major
senses, sound is used by many species for detecting danger, navigation, predation, and
communication. Earth's atmosphere, water, and virtually any physical phenomenon, such as fire,
rain, wind, surf, or earthquake, produces (and is characterized by) its unique sounds. Many
species, such as frogs, birds, marine and terrestrial mammals, have also developed special organs
to produce sound. In some species, these produce song and speech. Furthermore, humans have
developed culture and technology (such as music, telephone and radio) that allows them to
generate, record, transmit, and broadcast sound. The scientific study of human sound perception
is known as psychoacoustics.
Physics of sound
Spherical compression waves
The mechanical vibrations that can be interpreted as sound are able to travel through all forms of
matter: gases, liquids, solids, and plasmas. The matter that supports the sound is called the
medium. Sound cannot travel through a vacuum.
Longitudinal and transverse waves
Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called
compression waves. Through solids, however, it can be transmitted as both longitudinal waves
and transverse waves. Longitudinal sound waves are waves of alternating pressure deviations
from the equilibrium pressure, causing local regions of compression and rarefaction, while
transverse waves (in solids) are waves of alternating shear stress at right angle to the direction of
propagation.
Matter in the medium is periodically displaced by a sound wave, and thus oscillates. The energy
carried by the sound wave converts back and forth between the potential energy of the extra
compression (in case of longitudinal waves) or lateral displacement strain (in case of transverse
waves) of the matter and the kinetic energy of the oscillations of the medium.
sound 1 (sound)
n.
1.
a. Vibrations transmitted through an elastic solid or a liquid or gas, with frequencies in the
approximate range of 20 to 20,000 hertz, capable of being detected by human organs of hearing.
b. Transmitted vibrations of any frequency.
c. The sensation stimulated in the organs of hearing by such vibrations in the air or other
medium.
d. Such sensations considered as a group.
2. A distinctive noise: a hollow sound.
3. The distance over which something can be heard: within sound of my voice.
4. Linguistics
a. An articulation made by the vocal apparatus: a vowel sound.
b. The distinctive character of such an articulation: The words bear and bare have the same
sound.
5. A mental impression; an implication: didn't like the sound of the invitation.
6. Auditory material that is recorded, as for a movie.
7. Meaningless noise.
8. Music A distinctive style, as of an orchestra or a singer.
9. Archaic Rumor; report.
v. sound·ed, sound·ing, sounds
v.intr.
1.
a. To make or give forth a sound: The siren sounded.
b. To be given forth as a sound: The fanfare sounded.
2. To present a particular impression: That argument sounds reasonable.
v.tr.
1. To cause to give forth or produce a sound: sounded the gong.
2. To summon, announce, or signal by a sound: sound a warning.
3. Linguistics To articulate; pronounce: sound a vowel.
4. To make known; celebrate: "Nations unborn your mighty names shall sound" (Alexander
Pope).
5. To examine (a body organ or part) by causing to emit sound; auscultate.
Phrasal Verb:
sound off
1. To express one's views vigorously: was always sounding off about higher taxes.
2. To count cadence when marching in military formation.
[Middle English soun, from Old French son, from Latin sonus; see swen- in Indo-European
roots.]
sound 2 (sound)
adj. sound·er, sound·est
1. Free from defect, decay, or damage; in good condition.
2. Free from disease or injury. See Synonyms at healthy.
3. Having a firm basis; unshakable: a sound foundation.
4. Financially secure or safe: a sound economy.
5.
a. Based on valid reasoning: a sound observation. See Synonyms at valid.
b. Free from logical flaws: sound reasoning.
c. Logic Of or relating to an argument in which all the premises are true and the conclusion
follows from the premises.
6. Thorough; complete: a sound flogging.
7. Deep and unbroken; undisturbed: a sound sleep.
8. Free from moral defect; upright.
9. Worthy of confidence; trustworthy.
10. Marked by or showing common sense and good judgment; levelheaded: a sound approach to
the problem.
11. Compatible with an accepted point of view; conservative.
12. Law Legally valid.
adv.
Thoroughly; deeply: sound asleep.
[Middle English, from Old English gesund.]
sound ly adv.
sound ness n.
sound 3
n.
(sound)
What is sound and How is sound produced?
In: Speed of Sound, Waves Vibrations and Oscillations [Edit categories]
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Answer:
Sound is a physical entity, unlike noise which is the perception of sound. Sound is an high
pressure wave front through a medium (such as air, or a liquid such as water, or a solid), wherein
the wave front is followed by a reciprocal pressure differential behind it. Sound is produced
when something disturbs the medium and sets in motion the molecules in the medium.
Frequently, (no pun intended) the wave front/reciprocal entity occurs as an oscillating wave,
wherein there are a series of wave fronts (peaks in pressure), followed by wave valleys (lower
pressure). The relative height of the peak translates to how much energy is in the wave (how
great is the pressure), and the closeness of peak to peak (spatially and temporally) indicates the
pitch.
Noise, is not a physical entity, but is the mental perception of the physiological response to
sound. A wave front is converted from mechanical energy in our ear into an electrical impulse in
the brain that analyzes the wave information. The interpretation of the wave front is subjective
and the brain may interpret the wave signature as speech, music, clapping, gunshot, hum, etc.
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Speech/language scienceswww.brocku.ca& hearing sciences in Canada Preprofessional
BA or Certificate
Brainwave Entrainmentwww.BrainwaveCollege.comLearn about the science behind
brainwaves and entrainment.
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Relevant answers:
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How is sound produced?
. The spread apart particles are an area of rarefaction. Sound is produced by the vibrations
of a body
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How are sounds produced?
to a given sound's timbre. Sound can be transmitted by materials other than air. Sounds
are produced

How sound is produced?
Sound is produced when an object hits or rubs against each other. Sound can also be
caused
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Sounds are produced by?
sound waves that produce vibrations that makes the tiny bone in your ear vibrate and the
nerve
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How do you sound produced?
sound produced through the vibrating object .
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