Welshsox
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How do you measure Musical Energy and thoughts on Mono
Freako
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Quote:
Hi

Listneing last night to a solo violin fill a large concert hall with the single brush of the bow against a string, it got me thinking what exactly generates the sound in an instrument ?

If we assume that energy has to be transformed into sound waves where does that energy come from in say a violin player ? the phyiscal energy expanded to draw a bow accross the strings is minimal yet it fills the hall with sound ?
(comments left out...)

Are you aware that the bow is treated with resin?

Welshsox
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How does that effect the energy ?

Freako
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It CREATES the energy! (= vibrations)

tomjtx
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Quote:

Quote:
Hi

Listneing last night to a solo violin fill a large concert hall with the single brush of the bow against a string, it got me thinking what exactly generates the sound in an instrument ?

If we assume that energy has to be transformed into sound waves where does that energy come from in say a violin player ? the phyiscal energy expanded to draw a bow accross the strings is minimal yet it fills the hall with sound ?
(comments left out...)

Are you aware that the bow is treated with resin?

Actually it is called rosin, a tacky wax like substance rubbed on the bow hair to create friction on the violin string causing the string to vibrate and produce sound.

Volume is controlled by the amount of pressure applied to the pad of the bow by the fingers.

Elk
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the phyiscal energy expanded to draw a bow accross the strings is minimal yet it fills the hall with sound ?


It does seem to be a product of magic. Just a little sweep of the arm by a talented violinist and the hall resonates.

I think it is a combination of factors, physical and emotional.

Violins are very efficient in their transmittal of energy, the hall is an efficient conductor, we want to hear the sound and hang on its production with held breath.

Also magical is when a clarinet begins a note so softly you cannot hear the attack. Suddenly there is a gentle sound, without beginning, filling the room.

Yet another: full orchestra and playing full tilt at 120dB. With eyes closed you can't pick out the sound of the flute. Yet, when you look at the flautist this provides just enough cues that you can now hear what the flute is playing.

j_j
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What am i missing ? by the above logic hifi is incredibly inefficient to a level that seems like 99% inefficient.

Good loudspeakers are, in fact, in the range of 1% to 3 % efficient, except for some "high efficiency" types.

j_j
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Yet another: full orchestra and playing full tilt at 120dB. With eyes closed you can't pick out the sound of the flute. Yet, when you look at the flautist this provides just enough cues that you can now hear what the flute is playing.

That is directly related to the talk I mentioned here for which the announcement was willfully harrassed off the board by malfeasant liars.

You can find the slide deck "why you hear what you hear" at www.aes.org/sections/pnw/ppt.htm and there is a pointer to an MP3 of the talk at the womb forums in the "university" area under "Seattle audio talk".

Contrary to what the liars and stalkers imagined, the talk is not an all-out attack on audiophiles, or anything of the sort.

Your flute example is exactly an example of focusing on specific features of an audio signal, resulting in specific sensation at the auditory object level.

Elk
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I would have guessed something like 5-10%

Nice intro to violin acoustics clicky

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I would have guessed something like 5-10%

Nice intro to violin acoustics clicky

Well, some thoughts to consider:

The "quietest audible sound" is circa 200dB below 1 atmosphere, so it's about 10^-10 atmosphere. That's pretty (*&(* small, in fact, it's nearly as small as the noise level due to the particle nature of the atmosphere inside the critical bandwidth at the ear-canal resonance frequency. We can almost hear the noise level of the atmosphere itself, at least if we have good hearing and we are in a place quieter than most any place on earth these days.

Now why was it I like to hang out in places like the middle of national parks, in a valley surrounded by mountains? Oh, wait, I know.

Now, let us consider LOUD. Say 90dB.

that's 104dB below 1 atmosphere. That's .00009 PSI

That's what LOUD is, guys.

Elk
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Small indeed!

Orfield Lab's anechoic chamber has an ambient level of -9.4dB.

j_j
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Quote:
Small indeed!

Orfield Lab's anechoic chamber has an ambient level of -9.4dB.

What weighting? A? B? For 20-20K flat, that would mean that the microphone had less area than an eardrum.

Elk
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I don't know. Good question. Steve Orfield is a hoot and would probably be happy to discuss it.

It's routinely mentioned as the quietest place on earth (Guiness world record) and is one of the cool local sound/audio places (Orfield bought Sound 80 - home of the first digital multi-track).

BTW, happy 30th anniversary (yesterday) of Funky Town, another Twin Cities product (shortly thereafter Prince made Minneapolis funky town.)

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