# Dictionary Definition

1 financially secure and safe; "sound investments"; "a sound economy" [ant: unsound]
2 exercising or showing good judgment; "healthy scepticism"; "a healthy fear of rattlesnakes"; "the healthy attitude of French laws"; "healthy relations between labor and management"; "an intelligent solution"; "a sound approach to the problem"; "sound advice"; "no sound explanation for his decision" [syn: healthy, intelligent, levelheaded]
3 in good condition; free from defect or damage or decay; "a sound timber"; "the wall is sound"; "a sound foundation" [ant: unsound]
4 in excellent physical condition; "good teeth"; "I still have one good leg"; "a sound mind in a sound body" [syn: good]
5 reflects weight of sound argument or evidence; "a sound argument" [syn: reasoned, well-grounded]
6 having legal efficacy or force; "a sound title to the property" [syn: legal]
7 free from moral defect; "a man of sound character"
8 (of sleep) deep and complete; "a heavy sleep"; "fell into a profound sleep"; "a sound sleeper"; "deep wakeless sleep" [syn: heavy, profound, wakeless]
9 thorough; "a sound thrashing"

### Noun

1 the particular auditory effect produced by a given cause; "the sound of rain on the roof"; "the beautiful sound of music" [ant: silence]
2 the subjective sensation of hearing something; "he strained to hear the faint sounds" [syn: auditory sensation]
3 mechanical vibrations transmitted by an elastic medium; "falling trees make a sound in the forest even when no one is there to hear them"
4 the sudden occurrence of an audible event; "the sound awakened them"
5 the audible part of a transmitted signal; "they always raise the audio for commercials" [syn: audio]
6 (phonetics) an individual sound unit of speech without concern as to whether or not it is a phoneme of some language [syn: phone, speech sound]
7 a narrow channel of the sea joining two larger bodies of water [syn: strait]
8 a large ocean inlet or deep bay; "the main body of the sound ran parallel to the coast" adv : deeply or completely; "slept soundly through the storm"; "is sound asleep" [syn: soundly]

### Verb

1 appear in a certain way; "This sounds interesting"
2 make a certain noise or sound; "She went Mmmmm'"; "The gun went bang'" [syn: go]
3 give off a certain sound or sounds; "This record sounds scratchy"
4 announce by means of a sound; "sound the alarm"
5 utter with vibrating vocal chords [syn: voice, vocalize, vocalise] [ant: devoice]
6 cause to sound; "sound the bell"; "sound a certain note"
7 measure the depth of (a body of water) with a sounding line [syn: fathom]

# User Contributed Dictionary

## English

### Pronunciation

• /saʊnd/, /saUnd/
• Rhymes: -aʊnd

### Etymology 1

sund.

1. Healthy.
He was safe and sound.
2. Complete, solid, or secure.
Fred assured me the floorboards were sound.
3. In the context of "British|slang": Good or a good thing.
"How are you?" - "I'm sound."
That's a sound track you're playing.
##### Translations
healthy
• Finnish: terve, hyväkuntoinen
• Japanese: 健康
• Kurdish:
Sorani: ساغ, سه‌لیم
• Russian: здоровый, крепкий
complete, solid, or secure
• Danish: solid, sikker, pålidelig
• Finnish: hyväkuntoinen, terve
• Japanese: 健全, 堅固
• Portuguese: completo, sólido, seguro
• Russian: крепкий, прочный, надёжный
UK, slang: good or a good thing
• Danish: fornuftig
• Finnish: kondiksessa
• Russian: хорошо

### Etymology 2

#### Noun

1. A sensation perceived by the ear caused by the vibration of air or some other medium. (He turned when he heard the sound of footsteps behind him.)
2. A vibration capable of causing this.
##### Translations
sensation perceived by the ear
• Danish: lyd
• Finnish: ääni
• Hindi: ध्वनी, आवाज़
• Japanese: 音
• Kurdish:
Sorani: ده‌نگ
• Latvian: skaņa
• Polish: dźwięk
• Russian: звук
• Sanskrit: स्वर, शब्द, ध्वन्, नाद
• Urdu: aavaaz
vibration capable of causing this
• Danish: lyd
• Finnish: ääni
• Hindi: ध्वनी, आवाज़
• Japanese: 音
• Latvian: skaņa
• Polish: dźwięk
• Russian: звук
• Sanskrit: स्वर, शब्द, ध्वन्, नाद
• Urdu: aavaaz

#### Verb

1. To produce a sound.
When the horn sounds, be careful.
2. To convey an impression by one's sound.
He sounded good when we last spoke.
3. intransitive law To arise or to be recognizable as arising within a particular area of law.
"[T]here can be no doubt that claims brought pursuant to § 1983 sound in tort."
-City of Monterey v. Del Monte Dunes at Monterey, Ltd., 526 U.S. 687, 709 (1999).
4. To cause to produce a sound.
He sounds the instrument.
5. To state or utter, especially with deliberation; to repeat.
##### Translations
to produce a sound
to state or utter, especially with deliberation; to repeat
• Danish: udtale
to cause to produce a sound
law: to arise
• Japanese: 関係する

### Etymology 3

sund

#### Noun

1. : Long narrow inlet. (Puget Sound, Owen Sound, etc.)
##### Translations
long narrow inlet
• Danish: sund
• Finnish: lahti, vuono (fjord)
• Japanese: 入り江
• Russian: пролив, канал

### Etymology 4

, ultimately from subundare

#### Verb

1. : dive downwards, used of a whale.
The whale sounded and eight hundred feet of heavy line streaked out of the line tub before he ended his dive.
2. : probe
3. test
##### Translations
to dive downwards, of a whale
• Danish: dykke (ned)
• Finnish: sukeltaa
• Japanese: 潜る
to probe
• Danish: lodde, sondere, pejle
• Finnish: tutkia, kokeilla, sondeerata
• Japanese: 調べる, 探る
to test
• Danish: pejle, prøve
• Finnish: testata, koestaa
• Japanese: 調べる

#### Noun

1. A probe (e.g. a surgeon's tool)
##### Translations
a probe
• Danish: sonde
• Finnish: koetin
• Japanese: 探子

### Etymology 5

most likely from a slighty altered usage of Etymology 1

1. sound asleep; quietly resting, sleeping peacefully; undisturbed

# Extensive Definition

Sound''' is vibration transmitted through a solid, liquid, or gas; particularly, sound means those vibrations composed of frequencies capable of being detected by ears.

## Perception of sound

For humans, hearing is limited to frequencies between about 20 Hz and 20,000 Hz (20 kHz), with the upper limit generally decreasing with age. Other species have a different range of hearing. For example, dogs can perceive vibrations higher than 20 kHz. 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 have evolved to produce song and (in humans) speech. Furthermore, humans have developed culture and technology (such as music, telephony and radio) that allows them to generate, record, transmit, and broadcast sound.

## Physics of sound

The mechanical vibrations that can be interpreted as sound can travel through all forms of matter: gases, liquids, solids, and plasmas. However, sound cannot propagate through vacuum. The matter that supports the sound is called the medium.

### 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 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.
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 wave properties and characteristics

Sound waves are characterized by the generic properties of waves, which are frequency, wavelength, period, amplitude, intensity, speed, and direction (sometimes speed and direction are combined as a velocity vector, or wavelength and direction are combined as a wave vector).
Transverse waves, also known as shear waves, have an additional property of polarization.
Sound characteristics can depend on the type of sound waves (longitudinal versus transverse) as well as on the physical properties of the transmission medium.
Whenever the pitch of the soundwave is affected by some kind of change, the distance between the sound wave maxima also changes, resulting in a change of frequency. When the loudness of a soundwave changes, so does the amount of compression in airwave that is travelling through it, which in turn can be defined as amplitude.

### Speed of sound

The speed of sound depends on the medium through which the waves are passing, and is often quoted as a fundamental property of the material. In general, the speed of sound is proportional to the square root of the ratio of the elastic modulus (stiffness) of the medium to its density. Those physical properties and the speed of sound change with ambient conditions. For example, the speed of sound in gases depends on temperature. In air at sea level, the speed of sound is approximately 767.3 mph, in fresh water 3,315.1 mph (both at 20 °C, or 68 °F), and in steel about 13,332.1 mph. The speed of sound is also slightly sensitive (a second-order effect) to the sound amplitude, which means that there are nonlinear propagation effects, such as the production of harmonics and mixed tones not present in the original sound (see parametric array).

### Acoustics and noise

The scientific study of the propagation, absorption, and reflection of sound waves is called acoustics. Noise is a term often used to refer to an unwanted sound. In science and engineering, noise is an undesirable component that obscures a wanted signal.

## Sound pressure level

Sound pressure is defined as the difference between the average local pressure of the medium outside of the sound wave in which it is traveling through (at a given point and a given time) and the pressure found within the sound wave itself within that same medium. A square of this difference (i.e. a square of the deviation from the equilibrium pressure) is usually averaged over time and/or space, and a square root of such average is taken to obtain a root mean square (RMS) value. For example, 1 Pa RMS sound pressure in atmospheric air implies that the actual pressure in the sound wave oscillates between (1 atm -\sqrt Pa) and (1 atm +\sqrt Pa), that is between 101323.6 and 101326.4 Pa. Such a tiny (relative to atmospheric) variation in air pressure at an audio frequency will be perceived as quite a deafening sound, and can cause hearing damage, according to the table below.
As the human ear can detect sounds with a very wide range of amplitudes, sound pressure is often measured as a level on a logarithmic decibel scale. The sound pressure level (SPL) or Lp is defined as L_\mathrm=10\, \log_\left(\frac\right) =20\, \log_\left(\frac\right)\mbox
where p is the root-mean-square sound pressure and p_\mathrm is a reference sound pressure. Commonly used reference sound pressures, defined in the standard ANSI S1.1-1994, are 20 µPa in air and 1 µPa in water. Without a specified reference sound pressure, a value expressed in decibels cannot represent a sound pressure level.
Since the human ear does not have a flat spectral response, sound pressures are often frequency weighted so that the measured level will match perceived levels more closely. The International Electrotechnical Commission (IEC) has defined several weighting schemes. A-weighting attempts to match the response of the human ear to noise and A-weighted sound pressure levels are labeled dBA. C-weighting is used to measure peak levels.

## Equipment for dealing with sound

Equipment for generating or using sound includes musical instruments, hearing aids, sonar systems and sound reproduction and broadcasting equipment. Many of these use electro-acoustic transducers such as microphones and loudspeakers.

## Sound measurement

sound in Afrikaans: Klank
sound in Arabic: صوت
sound in Bengali: শব্দ
sound in Bosnian: Zvuk
sound in Bulgarian: Звук
sound in Catalan: So
sound in Czech: Zvuk
sound in Welsh: Sain
sound in Danish: Lyd
sound in German: Schall
sound in Estonian: Heli
sound in Modern Greek (1453-): Ήχος
sound in Spanish: Sonido
sound in Esperanto: Sono
sound in Basque: Soinu
sound in French: Son (physique)
sound in Irish: Fuaim
sound in Gan Chinese: 聲氣
sound in Galician: Son
sound in Korean: 소리
sound in Croatian: Zvuk
sound in Ido: Sono
sound in Indonesian: Bunyi
sound in Icelandic: Hljóð
sound in Italian: Suono
sound in Hebrew: קול
sound in Latin: Sonus (physica)
sound in Latvian: Skaņa
sound in Lithuanian: Garsas
sound in Lojban: sance
sound in Hungarian: Hang
sound in Macedonian: Звук
sound in Malayalam: ശബ്ദം
sound in Marathi: आवाज (ध्वनी)
sound in Malay (macrolanguage): Bunyi
sound in Dutch: Geluid
sound in Nepali: ध्वनि
sound in Newari: सः
sound in Japanese: 音
sound in Norwegian: Lyd
sound in Norwegian Nynorsk: Lyd
sound in Uzbek: Tovush
sound in Polish: Dźwięk
sound in Portuguese: Som
sound in Romanian: Sunet
sound in Russian: Звук
sound in Simple English: Sound
sound in Slovak: Zvuk
sound in Slovenian: Zvok
sound in Serbian: Звук
sound in Serbo-Croatian: Zvuk
sound in Sundanese: Sora
sound in Finnish: Ääni
sound in Swedish: Ljud
sound in Tamil: ஒலி
sound in Thai: เสียง
sound in Vietnamese: Âm thanh
sound in Turkish: Ses (enerji)
sound in Ukrainian: Звук
sound in Võro: Helü
sound in Contenese: 聲
sound in Zeeuws: Geluud
sound in Chinese: 声音
Italic text''