What is Sound waves: Definition and 332 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. P

    Solving a Physics Problem: Calculating Ambulance Speed with Sound Waves

    Hi, Can someone please help me with the following problem: Standing at a crosswalk, you hear a frequency of 560 Hz from the siren of an approaching ambulance. After the ambulance passes, the observed frequency of the siren is 480 Hz. Determine the ambulance's speed from these observations.
  2. E

    Why Can't We Hear Explosions from the Sun in Outer Space?

    This might be a silly question, but i just realized i don't really know why we don't hear the sound of explosions from the Sun. Well, we do know there is "almost" noting in outer space. But there still is not much resistance + matter for the oscillations to reach Earth.
  3. T

    Sound waves and location? with my phantom

    sound waves and location? please help with my phantom! Hi, Here is my problem strange as it may be: I have an old piano which due to it's age and condition, when played, emits no musical notes or musical sound it is more of an attractive antique furniture piece than anything. However, of...
  4. A

    Exploring Sound Waves: Can a 'Sound Mill' be Created?

    *please move if in wrong forum* Im taking the IB at a school in New York and every 11th grader has to do a project called Einstein on the Beach. It involves creating your own project and doing it on the beach that the school will travel to on a day trip. I am trying to come up with a good...
  5. T

    How Does Sound Wave Interference Occur Between Two Speakers?

    Here is a problem i do not know how to set up: Two speakers, driven by the same oscillator (f=200Hz). They are located on a vertical pole 4m from each other. A man walks straight toward the lower speaker, perpendicular to the pole. How many times will he hear a minimum in sound intensity and...
  6. R

    Sound waves & destructive interference

    There is a diagram in my book for this problem... I'll try my best to describe it! There are two speakers (A & B) that form a right triangle (at B) with the listener (C). Suppose that the separation between speakers A and B is 5.00 m and the speakers are vibrating in phase. They are playing...
  7. S

    Why Do Sound Waves Cancel Each Other Out?

    I'm confused by this problem: http://myspace.homelinux.com:32123/sound.jpg Can someone explain the solution and what's wrong with my reasoning? It takes 1.7/340 = .005 sec for the wave to travel the 1.7m. So for the waves to cancel woudn't .005 = T * 1/2 * n (where T is the period of the...
  8. K

    Solving a Doppler + Beat Frequency Problem for Bat Speed

    A bat flies toward a wall, emitting a steady sound of frequency 2.00 kHz. This bat hears its own sound plus the sound reflected by the wall. How fast should the bat fly in order to hear a beat frequency of 10.0 Hz? Give your answer to two significant figures. Take the speed of sound to be 344...
  9. S

    How Do Sound Waves Affect Emergency Responses and Wave Motion Calculations?

    Hi everyone! I need help on these two problems: 1.) A flower pot is knocked off a balcony 20m above the sidewalk and falls toward an unsuspecting 1.75-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...
  10. D

    Energy from Sound Waves? Is it Possible?

    Is it possible (or even practical) to create a device that can harness the power of sound waves?
  11. S

    How Do Sound Waves Interfere When Two Trumpets Play Together?

    Don't really understand the first part of the question. When 2 trumpets were sounded together, 6 beats were heard in 2s. If the frequency of one trumpet was 786Hz, what were the possible frequencies of the 2nd trumpet. I keep on gettin' 3+Hz but don't know if it's right.
  12. S

    Solving for Distance of Iceberg from Ship: North Atlantic

    A saling ship is traveling in the North Atlantic at night. The captain is worried about ice bergs, but has no radar. The captain sounds the ship's horn and hears the echo 2.4s later. If the air temperature is -10degrees Celsius, how far away is the iceberg. I think I know how to do it but...
  13. G

    Exploring the Paradox of Lost Energy in Sound Waves

    This is a simple question, but i can't seem to get my bearings right on it. Consider two speakers at essentially the same point emitting sound waves that are half a cycle out of phase but otherwise identical. Interference dictates that these two waves should cancel out. The resultant wave, now...
  14. A

    Calculating Well Depth: Solving for Standing Sound Waves at 48, 80, and 112 Hz

    There's this problem I'm having lots of trouble with. It is: A person hums into the top of a well and finds that the standing waves are established at frequencies of 48, 80, and 112 Hz. The freq. of 48 Hz is not necessarily the fundamental freq. The speed of sound is 343m/s. How deep is the...
  15. D

    Questions on Sound Waves in Solids | Abdullah

    I have three questions about sound waves. I could have asked my physics teacher but he fails to answer almost all the question out of our syllabus. :mad: 1- We have read that the speed of sound in solids doesn't depend on their desities. If that's the case then they depend on what thing...
  16. K

    Two Questions with Sound Waves

    >> A driver travels northbound on a highway at a speed of 23.0 m/s. A police car, traveling southbound at a speed of 42.0 m/s approaches with its siren sounding at a frequency of 2260 Hz. (a) What frequency does the driver observe first as the police car approaches and then as it passes...
  17. T

    Calculating Speed of Sound in Liquid: Learn How to Solve Sound Wave Problems

    A microphone is moving in air toward a stationary source of sound (speed of sound = 343m/s). The detected frequency is 82.7Hz greater than the emitted frequency. When the microphone moves at the same speed toward the same stationary source in a liquid, the detected frequency is only 21.6Hz...
  18. T

    Calculating Sound Level Increase in a Work Environment: A Machinist's Dilemma

    The graph shows the US Department of Labor noise regulation for working without ear protection. A machinist is in an environment where the ambient sound level is of 85dB, i.e., corresponding to the 8 Hours/day noise level. The machinist likes to listen to music, and plays a Boom Box at an...
  19. G

    Calculate Frequency of Reflected Sound Waves from Truck Moving at 38 m/s

    A stationary motion detector sends sound waves of 0.700 MHz toward a truck approaching at a speed of 38.0 m/s. The speed of sound in the air is 343 m/s. What is the frequency of the waves reflected back to the detector? I tried doing F=f((v+vo)/(v)), which becomes F=.7MHz((343+38)/(343)), and...
  20. H

    Question regarding sound waves

    Question regarding on sound waves. -------------------------------------------------------------------------------- Hello,I just join in as member yesterday.Sorry to interrupt that I have question to ask.Here's the question. 1.Two small speakers emit sound waves of different...
  21. F

    Can Sound Waves Break Glasses? All About Sound Waves

    Is it true that people can sing better inside a bathroom? How could that be? Other links in internet tells about that Walls of Jericho (Old TEstamament). Joshua and his men surrounded the city, blew their trumpets and shouted very loudly... then the wall crumbled... I always thought of...
  22. N

    Can light enegry or waves affects sound waves?

    is there any relations for light waves to affects sound waves? :biggrin:
  23. F

    What's the optimum air pressure for sound waves?

    what is the optimum air pressure for sound waves? is there a graph that i can look at that ranges from 0 bar (or whatever it's measured in) to such high pressure that the air is almost a solid. what would you measure the flow of sound waves in?
  24. anil

    Sound waves of stone in a well

    Hello I am trying to solve a problem: You drop a stone into a well and hear the splash 1.47 s later. How deep is the well? Answer is 10.2 but how do I solve it? D = (0.5) gt squared D = VT
  25. B

    Can the Brain Differentiate Individual Sound Waves in Superposition?

    how are we able to clearly distinguish two different sound waves - like when someone is talking to us while music is playing in the background... I've read it is due to the superposition principle which states that the waves combine and form a resultant wave that is the sum of the individual...
  26. O

    Understanding Sound Wave Energy: Impact on Speed, Frequency, and Wavelength

    How does the amount of energy effect a wave? Does it affect the speed or the frequency or the wavelength?
  27. S

    Can Sound Waves Be Used as a Renewable Energy Source?

    What about using soundwaves from mines and waterfalls as an energysource? you could put a membrane in the exit of the mine, or over a waterfall. Then we would get energy without killing the fish! How about periodically fill a volcano with saltwater and use the steam as an energysource like...
  28. Link

    Understanding Modulation of Sound Waves to AM/FM

    CAn someone explain how sound waves is modulated into Am and FM carrier waves? I only have a poor illustrarion i don't understand.
  29. G

    Coherence of Sound Waves: Myth or Reality?

    Can sound waves be created that are coherent in the same way that laser light is coherent? I would guess not, because sound is a compression of the air in which it travels and could not be directed. Does anyone know for sure? Thanks!
  30. N

    Can Sound Waves Travel Through Space and Time?

    I've been searching for a long time now, I hope some one knows something about it. I heard that when u speak the sound waves do not vanish, they go into outerspace and stuck there, now scienets are trying to find a way to get the sound waves back and hear what old people siad (specially...
  31. L

    Sound Waves from a loudspeaker

    I've been stuck on this one problem for a bit, any help is really appreciated. "A loudspeaker is placed between two observers who are 110m apart, along the line connecting them. If one observer records a sound level of 60.0 dB and the other records a sound level of 80.0dB, how far is the...
  32. K

    Sound waves and gravity question

    [SOLVED] Sound waves and gravity question Just a small question: are sound waves affected by gravity, and can thye have an initial and final velocity, or do they always have a constant velocity and do not need to accelerate?
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