"Back to audio, lets take a live trumpet as an example. I've read that it produces sound into the 50k-80k range. We don't hear that directly, but it seems reasonable that it's going to interact with the environment in some way we do detect. It could certainly excite lower resonances that we do hear..."
If ultrasonic frequencies in musical instruments produce artifacts in the audible range that's one thing - but the recording and playback systems don't need to capture the ultrasonics any more than we need to hear them - all they need to do is capture the audible artifacts to reproduce the true sound of the instrument that we are capable of perceiving.
If ultrasonic frequencies in musical instruments produce artifacts in the audible range that's one thing - but the recording and playback systems don't need to capture the ultrasonics any more than we need to hear them - all they need to do is capture the audible artifacts to reproduce the true sound of the instrument that we are capable of perceiving.
sdclc126 said:
I know what you're getting at, and for cases like an ultrasonic frequency exciting a wood panel in the recording studio I agree, but what if the effect is on the listener directly? What if the frequency needs to reach his ear? or skin? I'm not a scientist and I have no evidence that these things are indeed happening, I'm just saying I wouldn't rule it out without a lot more evidence.
Here's an interesting study that detected increased brain activity when hearing music with frequencies over 20k http://jn.physiology.org/cgi/content/full/83/6/3548
A good analogy - especially as I've seen written up (but haven't verified it myself) demonstrations of human visual perception of IR radiation. Much like the difference between casual and critical listening, it seems that we usually 'ignore' the IR, but if IR filter goggles are worn to exclude the rest of the spectrum, one gradually becomes aware of the radiation, and it's possible to see through 'opaque' screens, etc. It would thus, perhaps, be surprising if the IR (and by analogy, ultrasonics) didn't play a subliminal part in our ordinary perception.
Is it possible that the brick-wall filtering accounts in part for the often 'unsatisfactory' reproduction from digital sources? It would be quite easy to place such a filter in an analogue signal chain and to note any subjective difference (subject to the usual problems of double-blind testing, etc.).
One difference between light and sound outside the usual spectrum is that IR and UV can be absorbed, then re-radiated at a wavelength that the eye can see.
With sound we can observe a similar situation.
Picture the frustration we would go through reproducing 16hz from a pipe organ, to discover the wall panelling vibrating in harmony, with its overtones at 32, 48, 64 and so one, along with rattles as the plaster works loose from the studs. Room distortion.
The study into brain patterns is interesting. Physiotherapists use ultrasonic techniques for deep massage. The U/S energy causes muscle tissue to heat. They can be used to splash water from a bowl (how I used to test them!). Microwave ovens use RF energy to heat food via vibrational friction.
Subjecting the human body to ultrasonics will cause neural reaction, but that doesn't mean its the ears doing the reception.
Some musical instruments may produce energy at supersonic frequencies. Take into account the diminishing amplitudes of the harmonics, then allow for the loss in the microphones at those frequencies, and you are below the noise floor of the recording process. Gone forever if its digital.
And interesting comments about "s" sounds. Sibelence. Seems to me a fine line in speakers. They seem to have too much, or not enough. Here we are, worrying about what some of us think we cant hear, and we still have trouble with our F's and S's, T's and D's,
and that's only speech.
With sound we can observe a similar situation.
Picture the frustration we would go through reproducing 16hz from a pipe organ, to discover the wall panelling vibrating in harmony, with its overtones at 32, 48, 64 and so one, along with rattles as the plaster works loose from the studs. Room distortion.
The study into brain patterns is interesting. Physiotherapists use ultrasonic techniques for deep massage. The U/S energy causes muscle tissue to heat. They can be used to splash water from a bowl (how I used to test them!). Microwave ovens use RF energy to heat food via vibrational friction.
Subjecting the human body to ultrasonics will cause neural reaction, but that doesn't mean its the ears doing the reception.
Some musical instruments may produce energy at supersonic frequencies. Take into account the diminishing amplitudes of the harmonics, then allow for the loss in the microphones at those frequencies, and you are below the noise floor of the recording process. Gone forever if its digital.
And interesting comments about "s" sounds. Sibelence. Seems to me a fine line in speakers. They seem to have too much, or not enough. Here we are, worrying about what some of us think we cant hear, and we still have trouble with our F's and S's, T's and D's,
and that's only speech.
Jep. As most commercial pressure for innovation and development in the recent decades was on speech intellegibility in public address systems and came from broadcasting and sound reinforcement equipment companies, we now have studio/stage microphony and broadcasting/concert technology with a focus on speech and loudness.
Only very little effort seems to have been made in the professional recording and broadcasting industry to improve subersonic perception. Understandably, as it doesn't immidiately translate into money at the end of the day (whereas bad speech intellegibility does translate into immidiate loss).
Only very little effort seems to have been made in the professional recording and broadcasting industry to improve subersonic perception. Understandably, as it doesn't immidiately translate into money at the end of the day (whereas bad speech intellegibility does translate into immidiate loss).
hearing the invisible?
The main thing in any system is to reduce the distortion present. By reduction, I also do not mean merely acheiving low gross distortion figures, although that is not a bad idea - it has been shown that the spectra of distortion is perhaps as important as the absolute level(s) of distortion.
Once you have achieved "low distortion" (imho) only then does it make much sense to think about HF bandwidth.
To the extent that a single tweeter that happens to have extended (and clean) HF rolloff that same tweeter is likely to also be relatively lower in distortion, and as noted have less inherent phase shift in band - if that matters.
As already noted, there isn't anything but noise up there on redbook CDs.
Trumpets go supersonic in the mouthpiece, and yes they do produce a ton of ugly harmonics. Violins, another "acoustic" instrument - or any bowed stringed instrument - will also produce ultrasonics galore.
The issue of cost vs. value/return is always the same deal - you don't need high performance tires on ur "daily driver". One does need high performance tires on ur IROC race car, and better have them if you race.
----------------
I've not suggested this "test" recently...
Here's a really enlightening test to do at home:
- grab ur very bestest recording device (24/192 - computer/stand alone?) whatever that is.
- hang two mics OUT the WINDOW! (opposite sides or adjacent sides of a room are very good, if you can)
Now listen to the sound through your system - usually the windows need to be closed to prevent feedback. Note your system levels - don't change them. Listen for a good while. Now, play back ur ambient sound...
Report back.
(oddly, this seems to work equally well with cheapo mics as with really good mics, although it is better with better rather than worse mics...)
_-_-bear
The main thing in any system is to reduce the distortion present. By reduction, I also do not mean merely acheiving low gross distortion figures, although that is not a bad idea - it has been shown that the spectra of distortion is perhaps as important as the absolute level(s) of distortion.
Once you have achieved "low distortion" (imho) only then does it make much sense to think about HF bandwidth.
To the extent that a single tweeter that happens to have extended (and clean) HF rolloff that same tweeter is likely to also be relatively lower in distortion, and as noted have less inherent phase shift in band - if that matters.
As already noted, there isn't anything but noise up there on redbook CDs.
Trumpets go supersonic in the mouthpiece, and yes they do produce a ton of ugly harmonics. Violins, another "acoustic" instrument - or any bowed stringed instrument - will also produce ultrasonics galore.
The issue of cost vs. value/return is always the same deal - you don't need high performance tires on ur "daily driver". One does need high performance tires on ur IROC race car, and better have them if you race.
----------------
I've not suggested this "test" recently...
Here's a really enlightening test to do at home:
- grab ur very bestest recording device (24/192 - computer/stand alone?) whatever that is.
- hang two mics OUT the WINDOW!
(opposite sides or adjacent sides of a room are very good, if you can)Now listen to the sound through your system - usually the windows need to be closed to prevent feedback. Note your system levels - don't change them. Listen for a good while. Now, play back ur ambient sound...
Report back.
(oddly, this seems to work equally well with cheapo mics as with really good mics, although it is better with better rather than worse mics...)
_-_-bear
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