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. A

    Sound Engineering: Why's it so hard to get things like timbre right?

    Apologies if wrong forum. Could not see anything about acoustics. Is this mathematics? Why's it so hard to get things like timbre right? Digitised instruments and voice changers don't always sound right. I had a chance to visit a recording studio. Was given a lengthly talk about sound from a...
  2. Richard DiMaria

    The sound that rushing water makes

    What actually caused the sound made by rushing water, for example in rapids. Is it molecules bumping against each other? Or something else?
  3. snoopies622

    Confusion about the derivation of the speed of sound

    I've having trouble understanding a derivation of the speed of sound waves, which is actually similar to another derivation I found a couple days ago. Let's suppose the sound is moving through water in a long cylindrical horizontal pipe. The premises of the derivation are 1.) For a given...
  4. E

    Speed of sound in a relativistic fluid

    Let us consider the co-moving observer ##\mathscr{C}## for whom ##E = \epsilon## and ##\mathbf{\vec{V}} = \mathbf{\vec{0}}##. Doing the perturbation stuff to the first of the relevant equations gives$$\partial_t \delta \epsilon + \boldsymbol{\nabla} \cdot ([\epsilon + p] \delta \mathbf{\vec{V}})...
  5. T

    Equation of a sound wave with viscous damping in ideal gas

    How can we find a equation of a 1D sound wave in a non-differential form in an ideal gas with viscosity? How does the damping work? How does the wave lose energy at each layer as it propagates? To be clear I am looking for a simple exponential-sinusoidal function for it just in the case of...
  6. L

    Uncertainty of Speed of Sound in water, using Mackenzie's Equation

    I need to calculate the overall uncertainty of the value I have obtained for the speed of sound in water, using Mackenzies equation... I am not sure in what way to combine the above uncertainties. Any help would be greatly appreciated! Lloyd
  7. G

    Question sound hammer damage objects in room

    I was inside a closed room and I used a hammer in wood and metal, the noise and sound and sound waves generated by the hammer beating may have damaged and cracked objects and DVD discs that are inside the same room?
  8. Elsi b

    Superposition of the sound waves from two speakers

    Wavelength = 2L = 80cm
  9. H

    The intensity of the sound wave

    I = 1/2 ρvR²w² I = 1/2 *1.2kg/m³*340m/s*(10 x 10^-6m)²*(2π*440/s)² I = 0.16 W/m² This is my answer which does not match the given answer. Am I doing wrong?
  10. T

    I Speed of Sound & Light: Is it True?

    Are the following statements true? --------------------------------------------------------------- If a speaker and a listener are stationary with respect to the air, a listener will measure the speed of sound at about 343 m/s. Since the speed of a sound wave in air is dependent only on the...
  11. Pereskia

    Surprising sound frequency from a bottle

    Two of my pupils in secondary high school is doing a project on the sound generated by striking glass bottles drumsticks. They fill the bottle partially with water and strike the bottle with a drumstick and record the sound. Preliminary results: As long as the water level is in the cylindrical...
  12. Snoopy1234

    Sound transmission to the brain

    Water antenna Humantenna
  13. C

    Max velocity of a vibrating loud speaker membrane given sound intensity

    My attempt: p and T allows us to calculate ##Z=402 \frac{kg}{sm^2}## using ## Z=p*\sqrt(\frac{\gamma*M}{R*T})## . The sound intensity level at 10 meters allows us to calculate the intensity at 10 meters to be I=10``````^{-7} W/m^2 using ##50 = 10*log(I/I_0)##. Then, using the formula...
  14. R

    Solving for Time to Reach Ground: Calculating Velocity of Sound over 50m

    So I figured that to find how long did the ball take to hit the ground I would have to subtract 6 with the time it took the sound to reach back to the player. My givens are Velocity Intial = 330 m/s, speed of sound Δd = 50m Velocity Final = 0m/s because sound stops when it reaches the ear...
  15. E

    Signal Transmission Using Sound Waves

    Consider the following thought experiment... You are an engineer with a very peculiar assignment. With a mind to reduce the investment of excessive human labor and material waste, you have been asked to build an apparatus similar to an old-fashioned voicepipe. You are asked to ensure that the...
  16. Vivek98phyboy

    Contradiction in Phase of reflected sound

    While studying the fundamentals of sound waves in organ pipe, I noted that the fact about phase of reflected waves is contradicting while referring multiple sources This book of mine describes the reflection from a rigid surface/closed end to be in phase Whereas this one describes the...
  17. K

    How will the pitch of a string change when I stretch it? (sound)

    I was trying to search but found no results. Is there a way to calculate how frequency will change if I stretch a string by certain amount (0.14 mm in my case)? I found out I can measure its frequency once stretched, but no results as of how to estimate new frequency ahead of the time. I know a...
  18. J

    Frequency and Sound Wave Reflection

    I got that the sound wave will take 0.3s between the student and the left wall. It takes 0.5s between the student and the right wall. The first time these waves will coincide is 1.5s (5 trips for left side and 3 for right side). I then did 1/1.5 to get 0.67Hz. However, the answer is 6.67Hz. I'm...
  19. T

    Relaxation times of molecules during sound propagation

    So i understand completely what the first source is saying i.e. the longer the relaxation time, the more absorption of the ultrasound beam. The first paragraph of the second source however says the opposite- "very long" relaxation times mean the sound wave passage is unaffected? My attempt at a...
  20. P

    Sending a sound wave of 1cm wavelength through a 0.1Pascal medium

    I answered the first part of the question where I estimate the radius of ##O_{2}## is ##\approx 1.5 \times 10^{-10} \ \text{m}##: $$ p = \frac{KT}{l 4 \pi r^{2}} = \frac{(20+273.15)(1.38\times 10^{-23})}{(0.1)(4\pi)(1.5 \times 10^{-10})^{2}} = 0.143 \ \text{Pa}.$$ The confusion arises on the...
  21. T

    Amplitudes of longitudinal sound waves

    I'm coming back to physics after a long so apologies if this has a basic answer- How can the amplitude of a longitudinal sound wave be increased without increasing its wavelength? I understand what it would look like graphically if a low amplitude sine wave and high amplitude sine wave were...
  22. G

    B Speed of Light & Sound: Revolutionary Phenomenon?

    If sound (or any wave) was transmitted in a medium whose density was vanishingly low , would that wave propagate in the same way as em radiation in a vacuum? And vice versa does em radiation propagate in the same way as ,say sound so long as it is in a dense enough medium? In other words...
  23. K

    Does sound pass through bricks? Can I deflect sound away?

    I happen to live in a complicated neighborhood where people will have parties lasting all the night. I was thinking about accoustically isolating my bed room. Question 1: Intuitively, I would say that most of the sound comes through the windows, some through the door and a neglibible part...
  24. T

    Temperature and Sound Wave Velocity: Exploring the Proportional Relationship

    Apologies if this is a question with a basic answer, I'm coming back to physics after many years of being away from it! I read somewhere that for longitudinal sound waves traveling through air, if the temperature increases by 1 degree celsius then the velocity of the wave will increase y 0.6...
  25. aspodkfpo

    Sound waves affected by wind/sound waves in materials

    Are sound waves in air affected by wind? If the medium of the air propagation travels forward, does the sound also travel faster or is the sound simply vibrations in positions of space which disregard the movement of its medium. Would a transverse wave similarly move faster? If I was to...
  26. AN630078

    Sound Wave Interference and Finding the Path Differences with Diagrams

    Question 1: a. λ=v/f λ= 340/85 λ=4 m b. Please see attached. Ihave tried to accurately and to scale construct a diagram representing the compressions and rarefactions of the sound waves. Since the wavelength of a wave is simply the length of one complete wave cycle, and I have found that the...
  27. P

    Frequency of sound received by an observer

    My thought process was this, They are asking us to find the frequency of sound received by observer when the source reaches at origin. According to me when the source reaches origin there would be no component of source's velocity in the direction of observer, hence vs=0 vo=0 since the observer...
  28. pasomatt

    Assistance with Sound Wave Reduction/Amplification Experiment

    I was conducting an experiment with a tone generator (330 Hz) in boxes of different sizes with a glass plate placed on top of the box. There is a receiver about .55 meters away. Without any interference, the receiver registered -41 db +/- 1 db. When the tone generator is placed in the box and...
  29. R

    Is the following logically sound?

    Premise A: There is no future experiment that can be done at different constant speeds, that will give different results. Premise A leads to set of actions B: Theories, experiments, formulas. Set of actions B leads to conclusion C: Space is not a mechanical entity. Doesn't premise A already...
  30. P

    Stopping 80Hz Wave: Solutions to Eliminate Noise

    My neighbor has two AC condensers are driving me insane. I took measurements of the units, and they were between 33.5db - 47.9db at 80HZ. About 3 feet away is a cinderblock privacy fence between us. It is about 10 feet tall. His home is on an elevation about 4 feet higher than mine (so the...
  31. iVenky

    Why do beats sound pleasing to the ears?

    What's the reason why beats sound pleasing to ears? It looks like the tones that beat with each other a lot more in general sound pleasing.
  32. arm27

    Using Half of a Dome for Whispering Gallery Effect?

    I wanted to know what are the ways I can have someone speak normally and the other person in another section hear the sound? (there's no closed rooms but there are mirror partitions occasionally) So one of the things I thought of was using the whispering gallery phenomenon. To save space and...
  33. C

    Trig type question -- Speed of sound in water and in air

    unsure
  34. K

    Sound intensity - How to deal with decibels?

    I was looking up the maximal amount of noise allowed by current laws, that one can produce. I found that in my region one can produce sounds of up to 45 dB in the period from 22 pm to 7 am. But, it seems evident that the decibels fall off as we distance ourselves from the source. So shouldn't...
  35. J

    The hot chocolate effect to investigate the effects on speed of sound

    Summary:: The Hot chocolate effect is an investigation that extracts the essence about the effects on speed of sound. This is carried out in this sequence: A cup filled with liquid is continiously being tapped from the bottom. Meanwhile, a disturbance in the longitudinal sound waves is being...
  36. TechieDork

    How to not sound like I'm trying to "educate" or "lecture" someone?

    Whenever I try to explain something to some people. They often remark me I'm trying to "lecture" or "educate" them (they're all dean's listers).It surprised me because I thought they would be a quite open-minded folks. I tried to fix this by keeping my ego in checks , speaking in front of mirrow...
  37. B

    Speed of sound related to absolute temperature

    Here is the Q Very unsure about how to approach this question but this is what I have tried Any help would be really appreciated! Thanks
  38. S

    Curiosity - Relative speeds in relation to the sound barrier?

    So, I was reading through this thread: https://www.physicsforums.com/threads/would-a-portable-railgun-make-a-lot-of-noise.985309/#post-6309691 and I managed to make one of my usual questions which need more specific knowledge on the subject than I can find on the web. I (think I) understand...
  39. B

    Second highest frequency in a sound pipe

    So here is my question Have tried it and got these as my answers Have I done part b) correctly over here to find the 2nd highest frequency? Any help would be much appreciated! Thanks
  40. H

    Formula for calculating the wavelength of sound in interference

    Here is a diagram of experiment: Here is the results: Average distance between nodes (cm) Frequency (hz) Line 1 Line 2 Line 3 500 253 176 105 1000 333 438 None My analysis: ƛ/2=D ∴ƛ=2D where ƛ=wavelength (cm) D=distance between nodes/antinodes (the average,cm) 500hz: Line 1...
  41. M

    Formula for calculating wavelength of sound waves in interference?

    The values calculated was nowhere near the theoretical values, though I guessed they won't be as the results recorded was incredibly inaccurate. My teacher acknowledged the fact the final values won't be close to the theoretical ones but also said that my formula was wrong, that it works to find...
  42. danieluyter

    What is causing the square drop in my guitar effect's sine wave?

    I built a guitar (fuzz) effect, and analysed the sine wave from a tone generator through an oscilloscope. Wondering what the wave means and how it got to be the way it is. I will attach a picture of the oscilloscope screen + the circuit I used for the Fuzz effect. My question is what the cause...
  43. greg_rack

    Speed of sound in an ideal gas

    First of all I thought it was necessary to calculate the temperature(the only data missing for the formula) using the ideal gas equation(since I've already been given 'p' and 'V'), and plug it in the 'v' formula, but the problem immediately occurred when i tried to find out the number of...
  44. D

    Maths for Sound passing through different mediums

    What is the mathematics involved with calculating the energy lost from sound as it passes through different mediums? If I started off with a 70dB(A) sound wave, and after 0.5m it passed through 10mm of mild steel - what would be the sound level (in dB) 1m away from the steel plate? To clarify...
  45. Harini Krishna

    Calculating the speed of sound in water

    Hi,i want to calculate the speed of sound in water Containing Chlorine : 4mg/L in 1L distill Water Chloroamine : 4mg/L in 1L distill Water Florides : 0.5mg/L + in 1L distill Water Copper : 0.005mg/L + in 1L distill Water Lead : 1.3 mg/L in 1L distill Water Can you please help in...
  46. L

    What would teleportation sound like?

    I have a friend who has a film with teleportation in it, and when the people teleport, it makes no sound and doesn't have any effect on the area the teleporter left or arrived at. Since a teleporter leaving a location would create a vacuum the size of their body, and the air would quickly...
  47. DuckAmuck

    How Do Inelastic Collisions Distribute Energy Between Heat and Sound?

    In collisions that are inelastic or partially elastic, how can we predict how much of the energy lost to the surroundings becomes heat, and how much becomes sound? What determines that fraction?
  48. Just a dude

    Different Loudness Sound Waves and Destructive Inteference

    Summary:: Can smaller volume sound waves completely cancel out larger volume sound waves, and if not to what degree will the larger sound be canceled out. Hello everyone, just had a question regarding destructive interference. So I am in the process of writing/designing a sci-fi/fantasy power...
  49. Saptarshi Sarkar

    Time taken for sound to travel between two moving observers

    But the solution should be ##t_1 = \frac a {v_s - v_2}## I assumed the following - 1. I did not consider the frequency as the Doppler shift in frequency was not asked. 2. I did not add the distance the source moved in time ##t_1## to the total distance traveled by the wave as the pulse was...
  50. M

    Optimizing Marimba Tuning for Temperature Variations: A Scientific Approach

    I make marimbas, and I have invented a few variations (www.marimbaaustralia.com) I am interested in how sound moves through the wooden bars - in particular the effect that temperature has and how to compensate during tuning on different temperature days. I have almost no algebraic knowledge...
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