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. N

    I Does two-slit sound-wave interference pattern return to original form?

    Hello, I am reading about a sound wave that strikes two separated gaps/slits in a boundary. This causes two spherical waves to be created on the other side of the gaps that radiate outward, interfering with each other and creating an interference pattern in the resulting wave. The text states...
  2. S

    Correct statement about sound wave

    My answer is (1) and (2) but the teacher said it is only (1). I thought the speed of point at center of compression and center of rarefaction would be the maximum. Or the correct one is the speed at center of compression and center of rarefaction would be zero? Thanks
  3. V

    Direction of of the velocity vector for particles in a sound wave

    Using the equations mentioned under this question, I came up with following analysis and directions of velocities on either side of ##x_1##. Also, I'm not sure if there is an easier qualitative way to know the velocity directions rather than do a detailed Calculus based analysis?
  4. V

    Reflection of sound wave in an open organ pipe

    I know that standing waves form in an open organ pipe. Since, standing waves can only form from superposition of original wave and reflected wave, so there must be a reflected wave in an open organ pipe. But I fail to understand how sound wave can reflect at the open end of organ pipe.
  5. C

    I Equivalent formula for a Sound wave in a medium like an EM wave

    1.) In electromagnetics, wavelength in a medium is $$\lambda = \frac{\lambda_{0}}{n}$$, where $$n$$ is the refractive index. What is the equivalent formula for sound wave in a medium? 2.) Is there a reference sound velocity, like electromagetic wave speed in vacuum is $$c_{0} =...
  6. Afo

    Solving a Sound Wave Equation in Physics 1: Halliday, Resnick, and Krane

    Homework Statement:: This is from 5 ed, Physics 1Halliday, Resnick, and Krane. page 428 about sound waves I have highlighted the equation that I don't understand. How did the author get it? I understand how they get from the middle side to the RHS of the equation, but I don't understand how...
  7. E

    Location of the particles when 1.5 periods of a sound wave have passed

    qn iv. I understand that when 1.5 periods pass, every compression will become rarefaction, and every rarefaction will become compression(someone please correct if wrong) but the answer key shows something else. I'm interpreting the answer key drawing to be 1 compression and 4 rarefactions...
  8. 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...
  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. 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...
  11. 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...
  12. 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...
  13. 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...
  14. 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...
  15. A

    Why Can a Sound Wave Not Travel Faster than the Average Molecule Speed?

    I am having trouble understanding the following passage in my physics textbook, particularly the bolded sentence: "The speed of sound in a gas is closely related to the rms speed of the molecules of that gas. In a sound wave, the disturbance is passed from one molecule to another by...
  16. bubble-flow

    Oscillation of a particle inside water caused by a sound wave

    I don't really know where to start as this is not exactly my homework and I finished school some 15 years ago. I looked into my old high school notes, the last time I ever had anything about mechanical waves and sound. Unfortunately, we never learned anything about sound waves causing...
  17. G

    Calculating the Force of a Sound Wave on an Object

    Hello, I am going to be doing a project in which I'll be looking at how sound waves change the shape of an object. Specifically how sound waves can compress something. My question is, can I approximate a sound wave as a force in this case? I know a sound wave is much more complicated than a...
  18. S

    Sound Wave Problem -- time of flight in air versus in water

    Homework Statement Homework Equations v = d/t Solve for t. t = d/v The Attempt at a Solution In my General Physics 2 course we are doing sound waves I have the answer to the problem which is 90.8m I am trying to understand the concepts of sound wave. So please correct me if I am wrong, 1...
  19. G

    Sound Wave Interference Problem

    Homework Statement This is just a question about a question in Serway & Jewett's "Physics for Scientists and Engineers 3rd Ed". It's Objective Question 3 from Chapter 18, building on Example 18.1 from the text. Two identical loudspeakers placed 3.00 m apart are driven by the same oscillator...
  20. X

    Speed of a sound wave (compressibe flow)

    Hi, there is no particular question that I need help on, just something my lecturer told us in lesson which I couldn't quite understand so i'd like to check my understanding on this. I know that the speed of a soundwave is 'c' in undisturbed flow. Suppose the flow velocity is 'U'. If the...
  21. Cc518

    Calculating τ by knowing I is proportional to A^2

    Homework Statement A vibrating standing wave on a string radiates a sound wave with intensity proportional to the square of the standing-wave amplitude. When a piano key is struck and held down, so that the string continues to vibrate, the sound level decreases by 8.0 dB in 1.0 s. What is the...
  22. J

    Maximum gain possible by sound wave focusing

    Just like a concave mirror concentrates light, it can also concentrate sound waves. Ray diagrams like the following look as if all waves converge to a single point of INFINITE power density which of course is not true, probably because of the wave nature of light or sound. What is the correct...
  23. F

    Sound wave intensity (dB) and sound processing

    Hello Forum, A sound wave intensity (pure frequency) is proportional to the square of the wave pressure amplitude, i.e. ##I \approx p_0^2##, where ##p_0## is the pressure wave amplitude: ##p_0 sin(\omega t \pm kx)##. This means that the (gauge) pressure value goes larger (positive) and lower...
  24. jha192001

    Sound Wave Doppler effect question

    I have seen few examples on Doppler effect and i am confused about one such. We are standing on ground. If the source of sound S moves and Object O is stationary. We would presume the frequency as well as wavelength of sound be changed to the obeject O. But if O moves towards or away from S...
  25. betamu

    Frequency of Reflected Underwater Sound Wave

    Homework Statement The sound source of a ship’s sonar system operates at a frequency of 18.0 kHz. The speed of sound in water (assumed to be at a uniform 20°C) is 1482 m/s. What is the difference in frequency between the directly radiated waves and the waves reflected from a whale traveling...
  26. H

    Frequency for resonance to occur

    Homework Statement That is a speaker. Sound wave is sent out from spesker S into pipe of uniform thickness. Piston P move to left 1st resonance at 0.045 m 2nd resonance at 0.151 m Frequency of the sounx 1620 Hz Piston is stopped at the position that 2nd resonance occur Then, frequency...
  27. R

    Sound Wave Interference: Investigating Null Results with Sound Level Meter Data

    I collected this data by moving a sound level meter slowly through a total length of 0,75 meter between two speakers pointing towards each other. The wavelength of the sine waves was 0,343 meters and the frequency was 1000 Hz. The sound level meter measured the sound in dbA 20 times a second...
  28. aatari

    Sound wave Interference from Two Speakers

    Hi guys I am having trouble determining a quite spot based on where you stand in respect to distance from the speakers. I have solved the question below but I need someone to explain to me how the "n" value can be used to determine a quite or not-quite spot. Am I looking for whole numbers? If n...
  29. F

    I Need to Calculate the Speed of Sound for a Lab

    Homework Statement Calculate the speed of sound in the classroom. You can use: Tuning forks, water, beaker, pvc pipe, ringstands, etc. Homework Equations v = f(wavelength) For fundamental frequency: L = 1/4(wavelength) For fundamental frequency: f = v/4L The Attempt at a Solution Here is...
  30. K

    Pitch and amplitude of sound wave Vs its volume

    Hi. If I know the pitch and amplitude of a sound wave, will I be able to calculate its volume. I can understand volume of devices vary betwerb brands and other categories. For the sake of discussion, let's assume volume to be a consistent unit or if db is the right unit, let's take that.
  31. A

    Inverse phase sound wave where does energy go?

    2 sound waves that are mathematical polarities cancel each other out according to my audio engineering book. I thought energy cannot be destroyed, just changed. Am I wrong? What happens to the energy? Same question could be applied to matter and anti matter right?
  32. physea

    Exploring Sound Wave Pressures in Atmosphere: A Graph Analysis

    Sound waves transmit in atmosphere as dense and thin areas of air. Is there a graph showing the highest and lowest pressure of atmosphere for sound waves of various decibels?
  33. R

    Question about an armonic sound wave

    We usually describe the sound as an armonic wave while studying it's frecuency or wavelength. My doubt is if that means that we consider the air an ideal gas, so that it can affect to the result as a sistematic error. Thanks!
  34. D

    Do light and sound waves roll up and break like ocean waves?

    When sea waves approach the shore they roll up and break due to different velocities of water layers formed due to the gradual change in water depth. The highest wave peaks move faster than all other layers and thus falls down. All other layers fall the same way but in a delay. this ends up with...
  35. Baritone

    What is the Power of Sound Waves in a Tube Filled with Helium Gas?

    Homework Statement Suppose a tube is filled with helium gas at a pressure of 0.11MPa and a temperature of 297K. If a piston of area of 400mm2 at one end of the tube creates sound by moving sinusoidally with a frequency of 60Hz, creating a wave with amplitude of 3.8mm, what power goes into (I'm...
  36. T

    Maximum Amplitude of Sound Wave?

    This animation demonstrates a longitudinal wave by means of moving bars. I realized that if we increase the amplitude of the wave, the bars will eventually start passing through each other, which sounds (no pun intended) like an unphysical scenario. Does this mean that there is a cap, a...
  37. L

    Pressure variation with sound waves equation

    Homework Statement P(average) for a speaker is 10 W. Gamma is 1.4 (ratio of specific heats), molar mass is 28.8 g/mol, air temperature is 50F, and pressure is 1atm. Find Pmax at 100 I have this equation that gives Intensity = (Pmax^2)/(2*Rho*v) where rho is density, and v is speed of sound...
  38. 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...
  39. 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...
  40. 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...
  41. 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...
  42. 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...
  43. 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...
  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. F

    I A light wave and a sound wave travelling together

    If we could imagine a medium that could slow down light quite significantly, if a sound wave and a light wave were both passing through this medium, would the sound wave see the light wave passing by at the speed that light passes through that medium or would it see it passing by at the speed...
  46. S

    Doppler shift and change in intensity of a sound wave

    How are the intensity of a sound wave and the Doppler shift of frequency related togheter? That is, if the source or the observer are in relative motion, how does the intensity change? For a sound wave $$I=\frac{1}{2} \rho \omega^2 A^2 c=2 \pi^2 \rho f^2 A^2c$$ (##c## is sound speed, ##\rho##...
  47. N

    Sound Wave Energy Loss due to thickness of aluminum

    Hello everyone! I previously opened a thread asking about sound wave energy loss in aluminum discs based on thickness. I am looking to find out more about exactly how much using a disc that is twice the thickness of the other, (one is 1/8" and the other is 1/4") sound energy would be lost using...
  48. N

    Sound Wave Energy loss question

    Hello everyone! I am currently working on a project where I have a piezoelectric sound transducer connected to a glass tube via an aluminum disc. I got two aluminum discs with one twice the thickness as the other. I wanted to know which aluminum disc would work best, the thin one or the thick...
  49. i_hate_math

    Sound Wave Problem: Frequency of Note in Amphitheater

    Homework Statement A handclap on stage in an amphitheater sends out sound waves that scatter from terraces of width w = 0.967 m (see the figure). The sound returns to the stage as a periodic series of pulses, one from each terrace; the parade of pulses sounds like a played note. (a) Assuming...