What is Sound wave: Definition and 204 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. H

    Solving Sound Wave Confusion: Finding Intensity at Distance d_0 from Source

    Homework Statement In general, if a sound has intensity of beta dB at 1 m from the source, at what distance d_0 from the source would the decibel level decrease to 0 dB? Since the limit of hearing is 1 dB this would mean you could no longer hear it. Express the distance in terms of beta. Be...
  2. S

    Sound wave intensity of elephants

    Homework Statement There is evidence that elephants communicate via infrasound, generating rumbling vocalizations as low as 14hz that can travel up to 10km. The intensity level of these sounds can reach 103dB, measured a distance of 5.0m from the source. Deteremine the intensity level of...
  3. A

    Solving the Sound Wave Mystery: A Stone in a Well

    [SOLVED] Sound wave A stone is dropped from rest into a well. The sound of the splash is heard exactly 1.70 s later. Find the depth of the well if the air temperature is 12.0°C. Anything _s is the sound wave, anything _f is the stone falling I tried using these equations: v_s =...
  4. T

    Why Does Sound Intensity at Point P Equal I1 + I2?

    Suppose we have two source of disturbance to produce sound waves. The intensity of sound produced by the first source at P is I1, and the other intensity is I2. So what is the intensity at point P. I see many books saying that I=I1+I2. Can you explain why? net medium displacement vector...
  5. T

    How Is Sound Intensity Calculated at a Distance?

    sound wave of a source?? Homework Statement A sound wave radiates from a source to all directions, if the power of the sound is 200 watts then the intensity of the sound wave 100m from the source is what? Homework Equations is this question complete / incomplet? is it missing any...
  6. Ahmed Abdullah

    Why sound wave travels faster in humid air than in dry air?

    A:The answer is humid air is less dense. Q:But why humid air is less dense? A:Because water molecules have less mass than the average air molecules do. But It will happen if and only if the pressure is unchanged. Given that dry and humid air are both under the same pressure then we have...
  7. D

    Distance from Flash: Soldier 20°C, 6 secs After Cannon Fire

    1. A soldier hears the sound of the firing of a distant cannon 6.00 seconds after seeing the flash. If the temperature is 20 degrees Celsius, how far is the soldier from the flash? 2. D = R * T 3. Since the speed of sound at 0 degrees Celsius is 330 m/s, the speed of sound at 20...
  8. B

    Wishing Well (sound wave) problem

    Homework Statement When you drop a rock into a well you hear the splash 2.8 seconds later. How deep is the well? Homework Equations t = t1 + t2 d = .5 * g * (t1)^2 d = v * t2 The Attempt at a Solution since the time is so small i used the the second equation d = .5 * (9.81) (2.8)^2 = 38.45...
  9. K

    Sound wave and energy can you help me?

    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? P=IA=(intensity)(area) =2x10^(-3) * (pi (6x10^-3)^2) =2.2610x10^-7 W P=delta...
  10. R

    Help w/ constructive interference sound wave intensity

    The Problem : The sound wave with intensity 31 mW/m2 interferes constructively with a sound wave that has an intensity of 20 mW/m2. What is the intensity of the superposition of the two. I know that you can add the amplitudes for constructive interference or subtract for destructive...
  11. B

    How Do You Calculate the Distance of Sound Traveling Through Different Mediums?

    so i have some questions on how to set up this one problem on my homework. Here is the problem: A person sees a heavy stone strike the concrete pavement. A moment later, two wounds are heard from the impace: one travels through the concrete and the other through air, and the sounds are heard...
  12. S

    Sound wave thru a tube question

    I have two tubes. Both are 12 feet long. One is 4" diameter for its entire length. The other has a 4" diameter segment for 4 feet, expands to 5" diameter for 4 feet, then reduces back to 4" for the remaining 4 feet. If the same sound is injected into both tubes, will the sound exiting the...
  13. T

    Sound Wave Intensity/Sound Level

    The intensity of sound wave A is 100 times that of sound wave B. Relative to wave B the sound level of wave A is: a. -2 dB b. +2 dB c. +10 dB d. +20 dB e. +100 db Using 10logbase10(I/Io) - 10log(100/1) - Would the answer be 20 dB?
  14. B

    Can Sound Travel Fast Enough to Warn a Man of a Falling Flower Pot?

    A flower pot is knocked off a balcony 21.6 m above the sidewalk and falls toward an unsuspecting 1.79 m-tall man who is standing below. How close to the sidewalk can the flower pot fall before it is too late for a shouted warning from the balcony to reach the man in time? Assume that the man...
  15. L

    How Close is a Copper Bar to Breaking Under High Tensile Stress and Sound Waves?

    The tensile stress in a thick copper bar is 99.5% of its elastic breaking point of 13.0 X 10^10 N/m^2. A 500 Hz sound wave is transmitted through the material. (a) What displacement amplitude will cause the bar to break? (b) What is the maximum speed of the particle at this moment? Comments...
  16. M

    What are Affordable or Free Sound Wave Analysis Software Options?

    Hey :) Do you know any sound wave analysis software? I'm especially interested in freeware or quite cheap ones. I can't use such stuff like Matlab or Cooledit (as I've heard which now is called Adobe Audition ;) ). Greets, Murky
  17. S

    Calculating Acoustic Pressure for 10 W/m^2 of Intensity

    The velocity of sound in air of density rho=1.29 kg/m^3 may be taken to be 330m/s. Show that the acoustic pressure for the painfull sound of 10 W/m^2 ~ 6.5x10^-4 of an atm. (atm~10^5 N/m^2) What is acoustic pressure. This question is easy I am sure, but I don't really know what it is...
  18. C

    Sound wave reflection question

    Hello, I am working on a problem, how would the echoes from a large and small insect compare if they were the same distance from a bat? (from the bats point of view of course) I don't think they would differ at all. If the insects are not moving, then there would be no differance. The only...
  19. S

    Sound Wave Propagation problem

    Problem: The equation of a certain traveling transverse wave is y(x,t)=4.00sin(81.0(pi)t - 1.590(pi)x) where t is in seconds and x and y are in cenimeters. Find the speed of propagation, the period and the wavelength for these waves (express you answer in units of m/s) So, I know A...
  20. Y

    Sound Wave Loudness for Finite Waves

    I have asked this before, but I didnt get the answer I was looking for. I was told the sound wave loudness of a wave is proportional to the amplitude^2 . This is true to perfect waves. However, most sound waves in nature have compact base and are not of infinity length. Which means, what...
  21. Y

    Can Decibels Measure Sound Wave Loudness?

    How do you measure a sound wave loudness? Thanks in advance.
  22. Amith2006

    Frequency of sound wave in air

    Sir, Velocity of sound waves in air is 330 m/sec. For a particular sound in air a path difference of 40 cm is equivalent to a phase difference of 1.6 pi. What is the frequency of this wave? I solved it in the following way: Let d(phi) = phase difference, dy = path difference Here d(phi)...
  23. W

    Equation for Sound wave power.

    Was the formula tha links power and frequency (a formula that dosen't include intensity)?
  24. N

    Sound wave spreading radially question

    I have a question dealing with sound waves. This figure shows waves spreading radially outward from a coherent source located at the center. The center spot represents a coherent source emitting at a constant frequency. Black indicates maxima (positive peaks) and white indicating minima...
  25. N

    Sound wave question (dealing with a speaker)

    Hello all, I have another sound question: "If louder sounds have bigger compression waves, what does a speaker have to do in order to create louder sound?" Ok, so a speaker creates a sound wave by generating regions of high and low pressure. It is these regions of high pressure and low...
  26. L

    Can you help with these sound wave problems?

    Help With Sound Wave Problems! Hi...I'm studying for a test on soundwaves tomorrow, and I have questions on a few problems my teacher never reviewed. I'd appreciate it if someone could even answer one of them. Thanks! 1) At rest, a car's horn sounds the note A (440Hz). The horn is sounded...
  27. G

    What causes the change in sound frequency when tapping a stirred liquid?

    I have recently been wrestling with this little problem: I take a hot cup of powdered chocolate and stir it. I then tap the bottom of the cup repeatedly. The sound continues to increases in frequency/pitch as I continue tapping at a constant speed. After I stir the liquid, the sound...
  28. D

    Sound Wave Device: Answers Here!

    Hey guys, what is the name of the device that display sound waves as transverse waves on a screen? Thanks
  29. M

    How Do You Calculate Air Temperature from Echo Delay and Speed of Sound?

    i need some help with this question. "Jim is walking in a field and screams...the wall is 300 meters away it takes 1.7 seconds for the sound to come back...wat is the temperature in the air." so i tried it as: V=d/t ...= 300m/0.85s ...= 353m/s from there i think i have to...
  30. J

    Sound wave relative minima help

    Two speakers are drive by a common oscillator at 800 Hz and face each other a distance of 1.25 m. Locate the points along a line joining the two speakers where relative minima would be expected (v =343m/s speed of sound) How would I do this? I think I would just take part of the wavelength...
  31. S

    How do sound waves move so that a person behind me can hear me in an open field?

    I have been studying sound waves, however, i have not seen in my books nor online how sound waves "move." I know that sound waves are longitudinal waves, meaning, that they move parallel to the direction of displacement, but it seems like they just travel in one direction although they reflect...
  32. L

    Characteristic Line of a Sound Wave?

    Characteristic Line of a Sound Wave?? Okay, I have another fluids question: The velocity (u) caused by a rightward propagating wave in a gas is described by the nonlinear wave equation (du/dt) + [a + ((gamma+1)*u/2)]*(du/dx) = 0, where a is the speed of sound, gamma is a constant, and...
  33. H

    Energy Absorbed by Ear from 95-dB Sound Wave

    A 95-dB sound wave strikes an eardrum whose area is 5.0 x 10¯5 m². How much energy is absorbed by the eardrum per second? ...been stuck on this question for so long.
  34. D

    Got a Sound Wave Question for you thinkers

    Hey everyone, I got a question for you. I was working after school one day with my Physics professor and we came across a question that said more or less; which of the following wave phenomena can be demonstrated only by light and not by sound? The choices were polarization, interference...
  35. I

    Destructive Interference of a Sound Wave

    A sound wave with intensity 25 mW/m^2 interferes destructively with a sound wave with intensity 28 mW/m^2. What is the intensity of the superposition of the two? I've read through this section in my textbook three times now and I still have no clue as to how to go about figuring this out...
  36. T

    Power and Amplitude of sound wave

    For my homework, To find Amplitude of the wave, for a longitudinal wave traveling down a copper rod. Given: frequency, radius of copper rod, average power, Young's constant, density, wavelength. what equation should I consider? I'm thinking something like P=(omega*amplitud)^2 because I...
  37. Q

    What happens to the energy of a sound wave as it travels through air?

    When sound waves die out, what exactly happens to the energy? It dies out too or somehow loses energy as it travels through air, right?
  38. S

    Discover the Science of Sound Wave Cancellation | From Physics Forums

    https://www.physicsforums.com/showthread.php?p=787788#post787788" When two waves cross each other's path, even if they are identical, they won't just disappear. They'll set up standing waves where they are interfering provided they are identical. Beyond that they will continue on their...
  39. R

    Solve a Sound Wave Problem: Tuning Fork Frequency & Resonance

    Can somebody help mi out to understand more this problem. Open at both ends tube with variable length and vibrating tuning fork is helded near one end. Lenght is .5 meter when the sound intensity is maximum. Find wavelength of sound, tuning fork frequency, and frequency which produce...
  40. Y

    Why does sound wave over 20000Hz or lower 20 Hz

    Why does sound wave over 20000Hz or lower 20 Hz cannot produce the horizontal wave? Although this is the reason why people can't hear those sound waves, is there any reasons or theory that can explain this phenomenon?
  41. J

    Calculating Frequency and Distance of a Sound Wave

    A sound wave of wavelength 0.70 m and velocity 330 m/sec is produced for .50 s. A) What is the frequency of the wave? B) how many complete waves are emitted in this time interval? c) after .50 s, how far is the front of the wave from the source of the sound? AnsA) V= (Lambda)(f)...
  42. P

    What is the wavelength of the sound wave?

    Here's the problem: Two speaks side by side are separated by 1 meter. If the sound intensity is found to reach its first maximum when someone stands 1.0 meter directly in front of one of the speakers ( ie. perpendicular to the line between the speakers) what is the wavelength of the sound...
  43. L

    Sound wave and a light wave that pass through a piece of plastic

    Help Now Please! What happens to a sound wave and a light wave tht are trying to pass through a piece of plastic. I think that the light wave slows down and may eventually stop and thre sound wave will get faster. Is this for which of the following reasons: A. Sound travels faster...
  44. K

    OUNT OF POWER IN SOUND WAVESThe Intensity of Sound Waves

    >> A jackhammer, operated continuously at a construction site, behaves as a point source of spherical sound waves. A construction supervisor stands 52.0 m due north of this sound source and begins to walk due west. How far does she have to walk in order for the amplitude of the wave function...
  45. T

    Calculating Sound Source Distance and Power Output: A Comprehensive Guide

    I'm really confused on this one too.. The intensity of the sound from a certain source is measured at two points along a line from the source. The points are separated by 13.1 m, the sound level is 71.30 dB at the first point and 63.20 dB at the second point. How far is the source from the...
  46. H

    Sound wave questinos my tutor couldnt even figure out

    sound wave questions my tutor couldn't even figure out allright, well, i tried these problems, really thought i knew what i was doing, cause this section has been fairly easy, but i just can't get a couple of them! maybe you guys can help? 1 A stationary motion detector sends sound waves of...
  47. L

    Solving the Sound Wave Problem of Two Identical Violin Strings

    Two identical violin strings, when in tune and stretched with the same tension, have a fundamental frequency of 440.0 Hz. One of the strings is retuned by adjusting its tension. When this is done, 1.5 beats per second are heard when both strings are plucked simultaneously. -What is the...
  48. C

    Pressure Amplitude to Pa: 1E-7 atm Conversion

    Hi all, Pls kindly advise how do I convert Pressure Amplitude of 1E-7 atm to the correct pressure unit (Pa - pascal)? much appreciated cseet
  49. C

    Is the Density of Gas Always 1.29 kg/m³ in Harmonic Sound Wave Calculations?

    Hi all, can somebody advise on this, Equation: P (change in pressure) = p (density of gas)*w*v*s(max displacement amplitute) P = pwvs Needed to know, is the density of gas always at 1.29kg/m(3)? I've this following qeustion: A piston at one end of a long tube filled with air at...
  50. J

    Calculating Frequency of Sound Wave in Water

    Dear all, if a sound wave of 1.0 kHz in air strikes the surface of a lake and penetrates into water. How can find the frequency of the wave in water ?? and assume the speed of sound in water is 1500 m/s for all frequencies ! the frequency in air is equal to the frequency in water ...
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