What is Sound: Definition and 1000 Discussions

In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimetres (0.67 in). Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges.

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  1. F

    Duration of sound in our brain (0.1s)

    Hello, a certain sound remains in our brain for 1/10 of a second. The phenomenon of echo can happen only if the distance is at least 17 meters: we say the letter A, which remains in our brain for 1/10s, and the reflection (echo) of A arrives to our ear after that 0.1s...If the distance is...
  2. F

    Can a sound wave be transverse?

    Hello, Sound waves are always introduced as longitudinal mechanical waves: the medium particles oscillate in a direction parallel to the direction of motion of the sound wave. We can only hear sound frequencies between 20Hz and 20KHz. For us to hear these mechanical sound waves, the waves need...
  3. Thejas15101998

    What Causes the Sound of Water Unfilling From a Bottle?

    When we unfill a waterbottle, we here a periodic sound like- cloc.. cloc.. cloc..- How does this happen?
  4. H

    Sound underwater distance and decibels

    I was wondering if sound underwater traveled further than sound in air? It seems like it wouldn't do to viscosity. I know that it travels faster however. Lastly, is the online reasoning for why we can't hear sound as well underwater correct: the water vibration bypasses some of the sensory...
  5. V

    How a whistle produces a sound?

    I have 3 question: 1) How whistle produces a sound? I mean sport whistle with small ball inside. 2) How we whistle (by mouth)? 3) If you have a hole in exhaust tube in car. Many people say to me: "It is louder when the car drove long time. (a tube is hotter)" My easy question is, why? And what...
  6. S

    Acoustics and Fluid Flow - COMSOL 4.2

    Hello everyone, First of all I am new here~ Second, I would like to "prove" on COMSOL that soundwaves (sound vibration) can alter/reshape the fluid flow Can someone tell me the physics i should use as well as all the other parameters to make it work? if someone is more experience can they...
  7. B

    Gun sound -- frequency analysis

    Small caliber guns have higher magnitude at higher frequencies and larger caliber guns have higher magnitude at lower frequencies. is this true ? because I am not see this in my test: that is the fft of a 9MM gun, As one can see there are low magnitudes at low frequencies and higher...
  8. S

    Measuring the period of SHM using sound

    Hello! First time posting here. I'm studying the IB and need to complete my required experimental write-up. I am looking to replicate the well-known experiment that finds the value of g by investigating the relationship between period and length of string for a simple pendulum. 1. Homework...
  9. Vanadium 50

    SMART reporting and Hard Disk buzzing sound

    I had a drive that every few minutes makes a buzzing sound. Here's what SMART is telling me. ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000b 071 071 016 Pre-fail Always - 61213753 2...
  10. B

    Sound wave -- positive and negative frequency?

    does ever sound wave have a positive and negative frequency?
  11. B

    How can you identify the type of gun by the sound it makes?

    how can you identify the type of gun by the sound it makes ? Like if you had a recording of a gun shot but you Can't see the gun and you can find the bullet.
  12. A

    The longitudinal displacement of sound wave

    Homework Statement The longitudinal displacement of a mass element in a medium as a sound wave passes through it is given by s = sm cos (kx – ωt). Consider a sound wave of frequency 330 Hz and wavelength 0.95 m. If sm= 16 µm, what is the displacement of an element of air located at x = 1.1 m...
  13. Biker

    Answering Sound Wave Questions

    1) How good our approximations of thinking about waves as a function like sin? 2) The power of a sound wave, I have looked on the internet for derivations and all of them used calculus which is a quite expected thing so I skipped it because I still didnt take integration. However I found a proof...
  14. S

    Exploring the Difference Between Sound and Light

    While studying the difference between sound and light, I am puzzled by the following statement in this blog: Is this just another way of saying it doesn't need any medium? The Transmission medium Wikipedia page makes me think the vacuum of space is its "medium".
  15. T

    How long does it take for sound to travel 1 mile at a speed of 740 mph?

    Let's assume a speed of sound of approximately 740 mph at sea level. If I there are two aircraft traveling in formation 1 mile apart (one in front of the other) at 730 miles per hour, how long will it take for the sound of single gunshot fired from the trailing aircraft to reach the lead...
  16. B

    What (if anything) is sound made of?

    What(if anything) is sound made of?
  17. T

    Algorithm for dB vs time graph for one frequency from FFT?

    I'm doing a physics experiment for school, for which I am measuring the reverb time for specific frequencies in a room. What I did was record a 1000 Hz sound, and some time after it, and looked at its FFT on Audacity to see the intensity of just 1000 Hz at a given time. Manually, I can do this...
  18. K

    Automotive Can hot air replicate the sound effects of exhaust gases?

    Hey guys, is it possible to replicate the sounds produced by exhaust gases in a car by using only hot air? Thanks in advance for your responses.
  19. A

    Did I understand sound refraction (am I doing it right)?

    Homework Statement Moving through air, a wave hits a steady area of water with a angle of 13°. The velocity of the wave in air is 550 m/s and in the water 1650 m/s. What is the refraction angle of the wave? Does the angle move away or to the line of symmetry? Btw. I think I translated it...
  20. S

    Hardware that can produce sound waves with frequencs 0-200hz

    i'm doing an experiment to study the effect of sound waves on fire and smoke and would like to know how can i produce sound waves with frequencies varying from 0-200 hz
  21. Surya97

    Why is there a set speed of sound in a certain medium?

    Why does sound always move at the local speed of sound in a medium (in other words, why is there a set speed of sound for certain medium)? I understand that sound is a compression wave, but shouldn't a louder sound (i.e. one with a higher amplitude) move faster? What about a higher pitch noise...
  22. huffy

    What is the wavelength of a sound wave?

    Homework Statement Alas, after a sybaritic festival, the cheap upright piano in your fraternity house is found upright at the bottom of the house swimming pool. You decide to play Handel's Water music but first test the sound of middle C (261.6 HZ). The speed of sound in water is...
  23. B

    Cool sound generator project

    So I have working code of a : FFT Digital low pass and high pass filter and sound generator What cool projects can I make which these ?
  24. F

    What hardware is needed for analyzing sound signals?

    Hello everyone, I am interested in analyzing sounds (both spectral plots and time plot). What type of hardware would I need? There are a lot of free softwares online... Are there educational hardware tools that are not too expensive? thanks!
  25. Pambos

    Intensity of sound wave and energy

    Homework Statement A sound wave with intensity 2x10^(-3) W/m^2 is perceived to be modestly loud. Your eardrum is 6.0 mm in diameter. How much energy will be transferred to your eardrum while listening to this sound for 1.0 min? Homework Equations P=IA=(intensity)(area) =2x10^(-3) * (pi...
  26. Y

    Sound Pressure in Partial Vacuum

    Is there a good description or formula regarding how the sound pressure from a constant source depends upon ambient pressure? That is, if I were to conduct an experiment where I put a source and a microphone in a container, and then change the pressure in that container with a pump, assuming...
  27. W

    Checking Windows Registry for Sound Settings

    Hi All, I am having trouble with my sound ( no output) and, after trying all the obvious things and more, I am trying to see if the registry settings (which contain initialization info for devices, among other things). Does anyone know how to check these settings for sound devices? Thanks.
  28. W

    Question on destructive and constructive interference

    Homework Statement Two speakers A and B are 3.50m apart and each one is emitting a frequency of 444Hz. However because of signal delays, speaker A is 1/4 of a period ahead of B. Find all points relative to the centerline between A and B where there is constructive interference. Include angles...
  29. B

    Why sound produced by rapids varies in pitch based on height

    The other day I was at a river listening to some rapids. The sound produced by the rapids appeared to vary in pitch depending on how high up I was (squatting down to the ground and standing up produced about a fifth in the variation of the pitch); and I can't think why it should be? Many Thanks
  30. A

    Find Well Depth from Time Taken to Hear Stone Hit Bottom

    Hello. This is my first post so I apologise if I've put it in the wrong category or done something wrong. Today in my physics lesson I was given a question where we were supposed to find the depth of a well, and we were given the suvat equations. The question was as follows: "A stone is...
  31. L

    How does flow of current result in sound?

    I understand in a bulb when electrons flow they cause resistance and this heats up the bulb and the gases inside are ionised and they in turn emit light because their atoms become charged. How does flow of electrons cause sound? I know its an advanced explanation but what is the flow actually...
  32. blue.flake

    What is the period of the loaded tuning fork?

    Two identical tuning forks vibrate at 256 Hz. One of them is then loaded with a drop of wax, after which 6 beats/s are heard. The period of the loaded tuning fork is? So, as the uploaded pictures shows, I did solve the problem, but I'm not sure why the f1 frequency is bigger than f2. I mean how...
  33. Hamal_Arietis

    Does the velocity of sound change when the source moves?

    Homework Statement Will the velocity of sound change if the source moves? Homework Equations The velocity of velocity of sound in air equals: $$V=\sqrt{\frac{\gamma RT}{M}}=const$$The Attempt at a Solution I think it doesn't change. But it seems to conflict with the equation ...
  34. H

    Question about Inverse Square law and sound intensity

    Homework Statement For school, I have to make a task about sound intensity and the distance to the sound source. I have to prove that the relation between these two is known as the inverse square law _1/ I_2 = ( _2/_1 )². Does someone know how I can plot the inverse square law or prove that it...
  35. ChloeYip

    Solving the Sound Level Problem: An Introduction to Environmental Engineering

    Introduction to environmental engineering 1. Homework Statement A sound level reading of 132 dB was taken near a construction site where some chippers were being used. When only one chipper was working, the sound level reading was 122 dB. Assume that all the chippers are located at the same...
  36. Clara Chung

    2 Sound waves reflection easy problems

    Homework Statement Refer to the photos, question 21 and 22(the one with a helicopter) Homework Equations Both answers are A The Attempt at a Solution for question 21, if the counts to ten, there are 9 intervals. I divide 20 by 9 and divide it again by 2 and get 1.1s not 0.5s. for question 22...
  37. R

    Why don't bowed musical instruments deaden their sound?

    Horsehair is a string of tiny bead-shaped growths -- from what I have read. Even that slides over strings until rosin allows the "beads" to grab temporarily. But if one bead pulls and releases the string, wouldn't the other strings in the horsehair "hank" dampen that sound? It obviously doesn't...
  38. donaldparida

    B Difference between note, tone and mode

    In physics, wave mechanics and vibration specifically, do the terms note, tone and mode mean the same thing or do they refer to difference things? Also what does the mode of oscillation exactly mean?
  39. S

    Is the "clack" sound from Newton's Cradle periodic?

    They certainly do sound periodic from observation. But is there a particular formula that proves that sound from Newton's Cradle is periodic?
  40. nigol

    Transducer magnet and making sense of a sound pickup

    Hey I am a layperson, and have very little understanding of physics. I'm trying to understand the relation between a magnetic field and air and how they are similar or dissimilar in terms of disturbance in them. Let me lay out the context from which I came to think about the question...
  41. T

    Optimizing sound energy transfer through plastic medium

    Hi everyone, I am looking to improve the transmission of sound from a small 1/2" electro-mechanical transducer through a plastic medium (about 1/4" thick). I understand plastic is not a great medium for this but I do not have the ability to change this. The defacto setup doesn't work too...
  42. cyberdiver

    Why is my Sondhauss tube not producing any sound?

    I've been trying to make a Sondhauss tube lately. My setup is a 17-cm long Pyrex test tube with a small piece of steel wool as the stack. I've been holding the closed end over a gas stove on full heat with a pipe wrench, but absolutely no sound is produced. What I am doing seems to be no...
  43. E

    Sound waves in a 'compressed' liquid

    Hi, I have a general question I was thinking about... So, in a liquid the particles are already very close together and as a result they are, in effect, not compressible. That being said, if we take water, for example, it is possible to compress is slightly. It requires, however, a great deal...
  44. Kanad

    What is the relationship between wavelength and compression in sound waves?

    Just a quick question. Wavelength is defined as the distance between two crests of a wave, so in a sound wave, is the wavelength the distance between two compressions.
  45. shawn9521

    I Understanding the Doppler Effect: Exploring Sound Waves on a Moving Object

    Let's say you have a sound emitter and receiver a fixed distance apart on a moving object but open to the air, such as on the hood of a car. The emitter is near where the windshield wipers are, and the receiver is closer to the grill. They are in aligned along middle of the car, longitudinally...
  46. R

    Units of sound pressure level, example: 120 dB re 20 μPa

    I am trying to do a calculation using a value of -211dB re uPa/V , are these SI units? i.e. if OCV = -211db re uPa/V and I have RL = 20log(Vrms) - OCV Do I need to convert the OCV to standard units before putting it in the equation? Wiki isn't so clear about this:
  47. kolleamm

    Do liquids absorb sound better than solids?

    I'm brainstorming ideas on how I could possibly create a sound proof box to block out the noise from my servo. I was thinking to create a plastic box with hollow walls that could be filled with some sort of liquid, not water, but maybe something with low viscosity to absorb the sound. Would...
  48. H

    I Is it possible to image individual air molecules?

    I was wondering if it is possible to image the motion of individual air molecules? What I am picturing is using a laser to illuminate a volume of air, and using scattered light to measure the velocity of individual air molecules through the doppler shift of the scattered light. It seems that...
  49. A

    How to find the sound power in a collision?

    How would you go about calculating the sound power and sound pressure given the pressure (as in collisions [force/area]) of the collision, kinetic energy in the collision, velocities of both objects, densities and masses. Is this possible? Is the pressure of the collision equal to the sound...
  50. T

    How do different path differences affect interference in sound waves?

    Homework Statement Two loudspeakers, A and B, are driven by the same amplifier and emit sinusoidal waves in phase. Speaker B is L = 2.00 m to the right of speaker A. The frequency of the sound waves produced by the loudspeakers is f = 206 Hz. Consider point P between the speakers and along the...
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