From: "grendeltooth" <grendeltooth@...>
Walt wrote:
The human ear does not hear such high frequencies, period. Even the listed 20hZ-20kHZ for human hearing is very misleading for anyone out of diapers. And the human brain averages what it hears, it certainly does not discriminate at a level of 1/96000th of a second.
I read somewhere that the human ear can detect impulses that, if they were a sustained waveform, would be well above 20 kHz and possibly into the 30 kHz range. Apparently this phenomenon is hard to measure because standard audio tests are not reliable for transients, I guess because they require the listener to listen for a while to be able to qualify or quantify what is heard.
This effect was given as a reason why some golden ear critics of audiophile equipment can rave about an amplifier or a cable with mediocre measurements, but has incredible life to it. Also I've heard some tube afficiandos say that hollow state has more pleasing transient response than solid state, this being another reason why tubes sound richer and more lifelike than transistorized equipment.
I don't intend to generate debate on amplifiers, wires, tubes vs solid state, and what constitutes "more lifelike." I hope this is not the forum for that. My point is that there may be yet good reason to design equipment with extended range and particularly good impulse characteristics.
Grendel
The audio tests that were used for checking range included monitoring brain waves. That's how we know what a newborn's range is. If there is no response in the brain, we can probably assume the sound was not heard.
I spent several years doing hearing tests on military volunteers and draftees in the late 60's. From that I can say the majority of the folks in their early 20's are at least 30-40dBA down in their hearing even at 5kHZ (many are already down 70dBA or more). And it only gets worse with age or increasing frequency. Very depressing to look at all those hearing tests. If you think you hear a lot above 10kHZ, go get a good hearing test and be highly depressed. That upper range is mostly in there because babies and young children hear those well.
I'm quite certain if you make it loud enough that ultrasound will be detected by us. Probably by the damage it will do. Something like noticing as your bones turn to powder..
While I'm not too much a believer in the "golden ear" folks (they have failed too often when tested blind), their abilities don't have anything much to do with frequencies above 20kHz. I believe whatever they have, it's a combination of good abilities to detect slight sound differences combined with a large experience with sound reproduced on different equipment. They have formed a yardstick that sound reproduced in a certain way on certain equipment is "perfect" or "best" and make their pronouncements based on how close the sound is to their ideal model. Due to the nature of this, their pronouncements will always favor older equipment. Note I think to become a golden ear type you will need to figure a way to overcome your mind's tendency to modify what we hear to suit our attitudes, or at least control it. That's a good thing to work on as a recordist.
Yes, there is good reason to design equipment well. My point was more that we can design for things that don't matter, wasting money and effort and are running off doing so while neglecting what does matter. How many are frantic to get themselves a 24/96 recorder to record from their DIY panasonic mic? Such things make no sense. Yes, it's fairly easy to design a digital recorder to sample more often and store more bits about each sample. But the input ahead of that is a considerable different story. Mic design has hardly moved forward in this area since it was for analog tape.
Note that until recently mics used to record music did not have at all decent characteristics above 20kHZ if they even approached that level. People are telling us about the wonderful things this extra frequency range and fast transient response gave them when the mics they used gave them garbage in that department. There are now a few mics designed as the first generation 24/96 mics. Go out and spend the big bucks on something like the Sennheiser MKH-800, which is at least designed to give reasonable response at higher frequencies. Then see just how much those high frequencies really added.
It is my understanding that extending the frequency range of the MKH-80 design to make the MKH-800 was not at all a straightforward process. Tiny variations in housing design were huge problems to overcome. I don't expect that 24/96 spec mics will be at all common or cheap any time soon.
Note that the place where higher bit depths and sampling rates really mean something is when a computer is busy munching on that soundfile. It gives a little better chance the good sound you feed it will survive. The input and output ends outside the computer are not too important compared to that as far as sample rates.
Walt
wwknapp@...
