What is Sound intensity: Definition and 117 Discussions

Sound intensity, also known as acoustic intensity, is defined as the power carried by sound waves per unit area in a direction perpendicular to that area. The SI unit of intensity, which includes sound intensity, is the watt per square meter (W/m2). One application is the noise measurement of sound intensity in the air at a listener's location as a sound energy quantity.Sound intensity is not the same physical quantity as sound pressure. Human hearing is sensitive to sound pressure which is related to sound intensity. In consumer audio electronics, the level differences are called "intensity" differences, but sound intensity is a specifically defined quantity and cannot be sensed by a simple microphone.
Sound intensity level is a logarithmic expression of sound intensity relative to a reference intensity.

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  1. P

    Solving Sound Intensity with 2 Shut-Off Engines

    Homework Statement A person is a certain distance away from a plane with three equally noisy engines at 120 dB. What is the sound intensity if two of the engines are shut off? Homework Equations B (in dB) = log I/Io The Attempt at a Solution using this equation: 120 dB = 10 log...
  2. E

    Solving Sound Intensity Problem: Tips & Ideas

    This problem for some reason is giving me serious problem: A 1.00 kHz tone issued from a loudspeaker has an intensity of 100. dB at a distance of 2.50 meters. If the speaker is assumed to be a point source, how far from the speaker will the sound (a) have an intensity of 60.0 dB and (b) be...
  3. M

    What is the optimal distance to increase sound intensity?

    You are trying to overhear a juicy conversation, but from your distance of 25.0 m , it sounds like only an average whisper of 25.0 dB . So you decide to move closer to give the conversation a sound level of 80.0 dB instead. how close should you come? d= ...
  4. U

    Calculate Distance between A & B: Sound Intensity Problem

    Hi I have a question here from a chapter on sound. I'm not sure on how to solve this, so I was wondering if someone here could please give me a hand. Thank You! Question: A point source at A emits sound uniformly in all directions. At point B, the listener measures the sound intensity to...
  5. S

    Sound Intensity of a howler monkey

    Homework Statement The howler monkey is the loudest land animal and can be heard up to a distance of 1.4 km. Assume the acoustic output of a howler to be uniform in all directions. The distance at which the intensity level of a howler's call is 49 dB, in SI units, is closest to: a...
  6. S

    Sound Intensity and sound proofing

    A recording engineer works in a soundproofed room that is 36.2 dB quieter than the outside. If the sound intensity in the room is 2.45 x 10-10 W/m2, what is the intensity outside? It seems so ez yet I'm getting the wrong answer ok so here is what I am able to do the difference of 36.2dB...
  7. P

    Sound Intensity and Sound Waves

    I am having trouble with these two problems.. 1.By how many decibels do you reduce the sound intensity level due to a source of sound if you quadruple your distance from it? Assume that the waves expand spherically. For this one do I have to find ratios of I1/I2 and then substitute it in...
  8. T

    Lowering Jet Sound Intensity Below Pain Threshold

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  9. S

    Finding Maximum Sound Intensity: How to Determine the Two Lowest Frequencies?

    Hello. I am totally stuck on this question. I don't even know where to begin. Any help would be appreciated: A spherical sound source is placed at P1 near a reflecting wall and a microphone is located at P2. The frequency of the sound source is variable. Find the two lowest frequencies for...
  10. S

    Sound Intensity of Piston in Engine at 8000 RPM

    consider a piston in an engine with a stroke of 86 mm and RPM 8000 which gives the frequency of sound it is producing(due to compression and decompression) to be 133 Hz and wavelength 2.57 m. Then the pressure amplitude turns out to be 20000 Pa and the intensity of the sound wave to be...
  11. B

    How Far Must a Helicopter Fly to Decrease Sound Intensity by a Factor of 4?

    I am confused about a homework problem and was hoping that maybe somebody here can help... Homework Problem When a helicopter is hovering 1090 m directly overhead, an observer on the ground measures a sound intensity I. Assume that sound is radiated uniformly from the helicopter and that...
  12. Y

    Sound Intensity Level Question

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  13. E

    Sound Intensity: dB vs dB(A) - What's the Difference?

    sound intensity level can be measured in dB & dB (A). What is the difference between the 2 scales?
  14. N

    How Do You Convert dB to W/m² in Sound Intensity Calculations?

    I have no idea what I'm doing wrong on this one. I'm having problems somewhere in the log conversions to W/m^2 I believe. A siren mounted on the top of towers produces a noise of 120 dB at a distance of 2 meters. Treating the siren as a point particle (and ignoreing reflection and...
  15. tandoorichicken

    What Intensity Is Needed for a 194 dB Sound Level?

    The upper limit of the intensity level of sound waves is about 194 dB. This intensity corresponds to 100% modulation of the air; that is, the amplitude of the pressure oscillations corresponds to that of atmospheric pressure. What intensity (W/m^2) would be required to generate this level of...
  16. S

    Does Doubling the Number of Flutes Double the Sound Intensity?

    If 2 flutist play their instruments together at the same intensity, is the sound twice as loud as that either flutist playing alone at that intensity? Why or why not?
  17. C

    Sound intensity and ocean microphone

    The problem states: A microphone in the ocean is sensitive to sounds emitted by popoises. To produce a usable signal , sound waves striking the microphone must have an intesity of 10.6 dB. If porpoises emit sound waves with a power of 0.0502 W, how far can a porpoise be from the microphone and...
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