Does sound decelerate after bouncing off of something?
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- Rad Grandad
- 38041 posts since 6 Sep, 2003 from Downeast Maine
of course as some of the energy is absorded by the wall
The highest form of knowledge is empathy, for it requires us to suspend our egos and live in another's world. It requires profound, purpose‐larger‐than‐the‐self kind of understanding.
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- KVRAF
- 6519 posts since 13 Mar, 2002 from UK
No. The spead of sound is dependant upon the medium through which it is transmitted.
If it is travelling at, say, 700 mph through air and hits a pane of glass and is reflected back it's amplitude will decrease but it's velocity will remain at 700 mph.
If it is travelling at, say, 700 mph through air and hits a pane of glass and is reflected back it's amplitude will decrease but it's velocity will remain at 700 mph.
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- Rad Grandad
- 38041 posts since 6 Sep, 2003 from Downeast Maine
you're probably right....I can't even spell phisi...phyz..phiza...one of those guys into physics...let alone being one...
The highest form of knowledge is empathy, for it requires us to suspend our egos and live in another's world. It requires profound, purpose‐larger‐than‐the‐self kind of understanding.
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- KVRist
- 109 posts since 12 Sep, 2002 from Glasgow, Scotland
If it did then an echo would change pitch!
"Everybody loves the sound of a train in the distance ... everybody thinks it's true." (Paul Simon)
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- KVRAF
- 25049 posts since 12 Jul, 2003 from West Caprazumia
noIvoryTickler wrote:If it did then an echo would change pitch!
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- KVRist
- 271 posts since 13 Aug, 2002 from Knowhere, Texas
I assume that the frequency doesn't actually change, but the perception of frequency changes. I know that when I yelled into the Grand Canyon as a kid, I could hear my voice get deeper and deeper as it drifted out. Maybe that has nothing to with this.
I don't think I've ever read anything that combines the doppler effect in reference to sound bouncing off surfaces.
"The Doppler effect, named after Christian Andreas Doppler, is the apparent change in frequency or wavelength of a wave that is perceived by an observer moving relative to the source of the waves. For waves, such as sound waves, that propagate in a wave medium, the velocity of the observer and the source are reckoned relative to the medium in which the waves are transmitted. The total Doppler effect may therefore result from either motion of the source or motion of the observer. Each of these effects is analyzed separately.
Doppler first proposed the effect in 1842 in the monograph Über das farbige Licht der Doppelsterne und einige andere Gestirne des Himmels (On the colored light of the binary star and other stars). The hypothesis was tested for sound waves by the Dutch scientist Christoph Hendrik Diederik Buys Ballot in 1845. He confirmed that the sound's pitch was higher as the sound source approached him, and lower as the sound source receded from him. Hippolyte Fizeau discovered independently the same phenomenon on electromagnetic waves in 1848 (in France, the effect is sometimes called "effet Doppler-Fizeau").
It is important to realize that the frequency of the sounds that the source emits does not actually change. To understand what happens, consider the following analogy. Someone throws one ball every second in your direction. Assume that balls travel with constant velocity. If the thrower is stationary, you will receive one ball every second. However, if he is moving towards you, you will receive balls more frequently than that because there will be less spacing between the balls. The converse is true if the person is moving away from you. So it is actually the wavelength which is affected; as a consequence, the perceived frequency is also affected."
http://en.wikipedia.org/wiki/Doppler_effect
I don't think I've ever read anything that combines the doppler effect in reference to sound bouncing off surfaces.
"The Doppler effect, named after Christian Andreas Doppler, is the apparent change in frequency or wavelength of a wave that is perceived by an observer moving relative to the source of the waves. For waves, such as sound waves, that propagate in a wave medium, the velocity of the observer and the source are reckoned relative to the medium in which the waves are transmitted. The total Doppler effect may therefore result from either motion of the source or motion of the observer. Each of these effects is analyzed separately.
Doppler first proposed the effect in 1842 in the monograph Über das farbige Licht der Doppelsterne und einige andere Gestirne des Himmels (On the colored light of the binary star and other stars). The hypothesis was tested for sound waves by the Dutch scientist Christoph Hendrik Diederik Buys Ballot in 1845. He confirmed that the sound's pitch was higher as the sound source approached him, and lower as the sound source receded from him. Hippolyte Fizeau discovered independently the same phenomenon on electromagnetic waves in 1848 (in France, the effect is sometimes called "effet Doppler-Fizeau").
It is important to realize that the frequency of the sounds that the source emits does not actually change. To understand what happens, consider the following analogy. Someone throws one ball every second in your direction. Assume that balls travel with constant velocity. If the thrower is stationary, you will receive one ball every second. However, if he is moving towards you, you will receive balls more frequently than that because there will be less spacing between the balls. The converse is true if the person is moving away from you. So it is actually the wavelength which is affected; as a consequence, the perceived frequency is also affected."
http://en.wikipedia.org/wiki/Doppler_effect
Your very silence shows you agree.-Euripides
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- KVRAF
- 6519 posts since 13 Mar, 2002 from UK
The doppler effect would only apply if the reflective surface were moving relative to the listener.
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- KVRist
- 271 posts since 13 Aug, 2002 from Knowhere, Texas
I understand.
Your very silence shows you agree.-Euripides
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- KVRer
- 6 posts since 4 Oct, 2005
Actually, that's right. A wave won't change frequency if it passes into a medium with a different sound speed. It will curve, though. Since wave speed doesn't actually change (i.e. no deceleration) upon reflection, I can't give a good analogy for reflection but for transmission, you can imagine a sound wave starting in air and then going into water. The sound beam will actually change angle, as predicted by Snell's Law (which you may have heard of).
There are 2 ways to change the frequency content of a wave: one is the doppler effect, where the source is moving. The other is a nonlinear process, which exists naturally in air but at such high levels you don't usually notice it. Other than that, wave speed and frequency are pretty much independent of one another.
Sorry- that's too much information but I couldn't resist!
There are 2 ways to change the frequency content of a wave: one is the doppler effect, where the source is moving. The other is a nonlinear process, which exists naturally in air but at such high levels you don't usually notice it. Other than that, wave speed and frequency are pretty much independent of one another.
Sorry- that's too much information but I couldn't resist!
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AdmiralQuality AdmiralQuality https://www.kvraudio.com/forum/memberlist.php?mode=viewprofile&u=83902
- Banned
- 6657 posts since 10 Oct, 2005 from Toronto, Canada
YES! (cuz presumably its moving slower than other sounds in the same medium, which of course is impossible, as it's not the sound that determines it's speed.. it's the medium)jens wrote:noIvoryTickler wrote:If it did then an echo would change pitch!
So, no, it doesn't change speed (or pitch) after bouncing, assuming it's bouncing into the same stuff it came from. It just loses some energy which makes it quieter (and quieter in different amounts across different frequencies... so a coloring effect. Many delays and reverbs include a low pass filter on the feedback section to simulate this coloring.)
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- KVRAF
- 25049 posts since 12 Jul, 2003 from West Caprazumia
you are quite obviously contradicting yourself...AdmiralQuality wrote:YES! (cuz presumably its moving slower than other sounds in the same medium, which of course is impossible, as it's not the sound that determines it's speed.. it's the medium)jens wrote:noIvoryTickler wrote:If it did then an echo would change pitch!
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AdmiralQuality AdmiralQuality https://www.kvraudio.com/forum/memberlist.php?mode=viewprofile&u=83902
- Banned
- 6657 posts since 10 Oct, 2005 from Toronto, Canada
No I'm not... Ivory Tickler said "IF it did". And I agree, IF it did (and it doesn't) it would change pitch (and it doesn't, so therefore it doesn't change speed)