开云体育

I have been reading the most interesting thread on this subject.

After 44 years of audio engineering including a big dose of psychoacoustic measurements, I have come to some conclusions.

I thought it would be boring to cut and paste so many fragments of remarks that others have made, so I'll work from memory. However, Walter Knapp has made many remarks that I agree with completely.
-----------------------------------

Way back when I was a young pup grad student in the WPI acoustics lab I did a research project on RIAA equalizers of different topology (vinyl playback) and also the same for tape playback. There were some listening tests conducted, presumably with good-hearing subjects, and listeners were able to hear differences on rapid A/B comparisons, but were unable to be so selective after several hours, or a day, between tests.

I also performed the classic test on them where the phase of one earphone is reversed and left that way during a musical selection. When it happens, the listener's face cringes and he/she reports something has happened but they can not tell exactly what. If after another delay of hours, you start the test with one earphone phase reversed, the listener is quite happy and can not tell something has happened.

The whole world knows that the ear is phase deaf, right? Even mentioning anything about phase sensitivity in an open engineering forum gets you 20 lashes from all of the great authorities present. Under the right circumstances, I believe that is not true.

In particular, when we do A/B comparisons using complex tones, like musical instrument sounds, we are assembling our notion of the tone out of the fundamental plus all of the partials. If we play the same tone through another system that has a different phase shift characteristic in the region of the partials, I say we can detect that. I could find no other explanation of why rapid A/B comparison testing could pick out such subtle differences on RIAA equalizers. These circuits did have different phase shifts in these frequency regions. The RIAA break points land right in the two regions of partials of strong low frequency and high frequency instruments.
--------------------------------

Carrying this further --

I think someone discussed a high-frequency 3dB bump as audible -- that may be an amplitude change that is barely detectable, but it is a lot of phase shift.

I remember a two-way acoustic-suspension loudspeaker made by Leak (UK) in the sixties that measured a dead flat amplitude response through the crossover region by sounded like hell to my ears on certain notes. I finally got to make careful phase response measurements - well, that was the answer.

Someone mentioned 44.1k vs 96k sample rate -- the anti-aliasing filters used in digital systems have significant phase shift beginning two octaves before cutoff. It does not surprise me that someone can detect different filter topologies on a rapid A/B test, especially if the cutoff frequency is 2.18 times higher.
---------------------------------

For about six years we had a joint acoustics engineering program between WPI and Bose. Bose was doing the in-house training anyway so I joined in with a bunch of WPI students, shared the teaching load, and had lots of fun doing it. Each year we would do the ABX experiment on the detectability of low-pass cutoff frequency. We used headphones that had known excellent HF output and a variety of musical materials. Statistically, it was shown repeatedly that it is pointless to extend the HF response for streaming music above 16KHz. Doesn't mean we should do that, but it was revealing.

As a professional audio engineer I am embarrassed by the existence of cables made of oxygen-free unobtainium and by engineers proclaiming that 100KHz response is absolutely necessary.

Besides, a long time ago I started listening to the content, and not the hardware (as long as it was "high quality" stuff). Maybe I'm showing my age!

Dick Campbell

Bad news, folks. Panasonic just announced that the 60AY mic capsule
will be discontinued

I think it is only the holders that are discontinued, not the mics themselves.

Dick Campbell

In reading some of the posts regarding the human hearing capabilities, I?ve
had a few thoughts. When a note is played on a piano (or any instrument) you
hear not only the frequency of the note you played, but many frequencies
above and below it that vibrate sympathetically. This phenomenon is known
as the overtone series. It is my belief that there are many freq. that
occur above the normal human hearing range that add tonal characteristics
via sympathetic vibration to the sounds that we are able to hear. I?ve done
no tests really, but in comparing audio at 24 bit/96khz to 24 bit/44.1 I
have found that the 24/96 recordings sounded more ?lifelike?, if that means
anything. It could just be my imagination as I?ve done no blind tests, but
I would say there is a very small noticable difference esp. regarding depth
of the recording.



any thoughts?
Jason

Hello,

Bad news, folks. Panasonic just announced that the 60AY mic capsule
will be discontinued as of Feb. 15, 2004.



Anyone know what they are replacing it with? It does not say on the
Panasonic site.

Darren

From: kikeg@...
Subject: Re: Human ear capabilities / cables ()
--- In micbuilders@..., Geoff Wood <geoff@p...> wrote:

Congratulations - you are either 10 or an exception.

I don't think so. I'm 32, and have not worked much in noisy environments nor been at many discos when younger. I can hear 18 KHz tones, not at faint levels, but not at insane levels either. However there's young people out there that can hear 19 KHz tones easily. My father is 60, and can't hear 13 KHz tones even when they are blasting my ears.

We live in such a noisy world it's a commonly held belief that we are safe at fairly high levels. That you have not worked in the even noisier environments does not mean you have not been exposed to damaging sound levels. In general, anything above 80dBA is enough to cause some damage.

Consider that most, even careful folks, like a sound level a little above that in their music listening. And as they age, the sound level they choose will creep up. Because we are used to our particular hearing loss we tend to take it as normal and use it as a yardstick as to what's loud.

Or that driving a car with the windows open will produce more than that. I have some of that one, my left ear is worse than my right by a little bit, and I think it's the driving.

A normal city street exceeds that level. Almost any power tool, even many household appliances exceed that level.

The list goes on and on, the modern world is full of dangerous sound levels that people hardly recognize. I have a sound meter I cart around in the course of my field recording. I often check sound levels and not just of what I'm recording.

Hearing loss is not generally a sudden thing. Your ability to hear in each of the subbands your physiology uses degrades relatively slowly. The question is not that you might hear at a frequency, it's how well you hear relative to set standards, or how well you hear that frequency compared to your best frequency band (usually in speech frequencies). As I noted earlier, I did hearing tests on the late teen age group, hundreds a day for several years. The pattern was that most could hear all frequencies that we tested, but higher frequencies had to be many dB louder than speech frequencies to be heard. Typical really good hearing in that group would have the 10kHZ band only down 10-20dB from the speech bands. Average in that group was down 30-50dB, and there were lots of folks more than 60 dB down. And that's 10kHZ, not all that high a frequency, it was worse for the 15kHZ, which was the highest we routinely tested.

At 32, I'm sure you have considerable falloff of hearing at higher frequencies. It would take running a accurate hearing test to quantify it, informal tests like you describe don't give a very accurate picture. As others have said, whatever it is, protect it like gold. It will get worse with age even if you do that, but don't protect it and it will get worse much faster.

I'm 59, and have been reasonably careful about my hearing. I can still hear 20kHZ. If you play it 70dB louder than the dB level I can hear at speech frequencies. I cannot hear 22kHZ at all. The thing I note about my hearing pattern is that the entire range from around 10kHZ up to 20kHZ has a very similar loss. Then below that my hearing improves fairly rapidly with decreasing frequency.

Walt
wwknapp@...

From: Bob Cain <arcane@...>

To believe that pure tone testing discloses the extent of
human hearing is to believe that the ear/brain is limited to
sinusoidal detection and discrimination. This has not been
proven by any means. It's rather like saying that the
discriminatory power of the eye could be disclosed by
measuring its response to featureless monochromatic
sources. There is as yet no reason to believe that the
ear/brain doesn't do other things like edge or feature
detection or wavelet like decomposition which may not be
triggered by sinusoids. In an evolutionary sense, the
production of sinusoidal stimuli is a _very_ recent
development and I have to wonder why the ear/brain would be
particularly sensitive to them other than as a side effect. That organ evolved in an environment of much more spectrally
complex stimuli and is more than likely to have evolved
means for detecting those natural stimuli which may well not
respond to a pure component of their spectrum.
With music I know for certain that I can hear effects of
equalization in the spectral region beyond that where I can
detect tones.
Bob

Science has studied our hearing to a great deal more depth than the pure tone hearing tests administered by audiologists to detect hearing loss. They are far more curious than just that.

Note farther that natural sound is a mixture of sinusoidal components, even sometimes in pure form, it's not some recent invention, it's been there as long as there was sound. Even the sharpest impulse fits that pattern.

You have no sensor endings in your ear to hear them. That's why you have a frequency limit. Even if the transmission linkage from eardrum to those sensors transmitted the vibrations you would not hear them. (that's been tested too, by bypassing the linkage which imposes it's own limits on hearing)

I tend to take the most stock in the tests where brain wave activity is monitored. This removes a lot of uncertainty about what the ear sent to the brain.

Note that such tests have been done on a variety of sound patterns. One part of what was being tested was how short a impulse triggered the ear. It has been tested.

Mark Twain once said:
"You can't depend on your eyes when your imagination is out of focus"

A corollary is:
"You can't depend on your ears when your imagination is out of focus"

Your brain is not telling you everything. It's telling what it thinks you want to hear. And then you farther interpret that.

Walt
wwknapp@...

--- In micbuilders@..., Geoff Wood <geoff@p...> wrote:

Congratulations - you are either 10 or an exception.

I don't think so. I'm 32, and have not worked much in noisy
environments nor been at many discos when younger. I can hear 18 KHz
tones, not at faint levels, but not at insane levels either. However
there's young people out there that can hear 19 KHz tones easily. My
father is 60, and can't hear 13 KHz tones even when they are blasting
my ears.

At "insane" levels, I can hear up to 20 KHz pure
tones.

More likely you are hearing distortion products from the amp or >

drivers.

I don't think so. I have used good quality source, amp and headphones
for those tests, and none of the two first show aliasing, out-of-band
artifacts or poor IMD at high frequencies on standard measurements
(CCIF IM test tones, tone sweeps). The headphones were Sennheiser
HD580. Also, very high frequency tones are more "felt" than heard,
it's a special perception inside your head (like a blade in your
brain), that is quite disgusting. I think IM products wouldn't sound
that way. Anyway, I didn't perform the measurements when putting out
such insane levels, so it's certainly possible that the amp didn't
behave as in regular conditions, but I'm almost sure this was not an
issue, but I guess I should check it to be totally sure.

However, I can't hear a lowpass of 18.5 KHz on any complex
real-world music I've tried, at any listening level that I could
bear. The most I've been able to detect in a blind test is a

lowpass

at 18 KHz, using very special music with very loud high frequency
content, and struggling a lot.

Possibly also explained by out of band effects of the filtering.

I used a 1024-point linear phase FIR filter with more than 100 dB SNR
(Cool Edit Pro 1.2a FFT filter). This and similar test files are
available at

--- In micbuilders@..., Bob Cain <arcane@a...> wrote:

With music I know for certain that I can hear effects of
equalization in the spectral region beyond that where I can
detect tones.

I can't, for sure. At "sane" listening levels, I can hear pure tones
up to 18 KHz easily. At "insane" levels, I can hear up to 20 KHz pure
tones. However, I can't hear a lowpass of 18.5 KHz on any complex
real-world music I've tried, at any listening level that I could
bear. The most I've been able to detect in a blind test is a lowpass
at 18 KHz, using very special music with very loud high frequency
content, and struggling a lot.

This is very consistent with known human auditory physiology, and the
reason is auditory masking. Low and medium frequency content masks
very easily high frequency content, thanks also to Fletcher-Munson
curves, and in fact, there's not much real-world music where a
lowpass at 16 KHz can be heard.

Some examples:



This castanets samples has impulsive high-frequency content up to 19
KHz, but I can't hear a lowpass at 15 KHz at all, even I have to
struggle to hear the 12 KHz lowpass.

If you have a 96 KHz soundcard, you can try the samples at:



And see for your self if you can tell the samples with content beyond
20 KHz from these same ones but without content beyond 20 KHz. I
can't, and I've not heard about anyone who can.

There are mainly two reasons why some people seems to be able to hear
a difference in response over 20 KHz: because there are other changes
below 20 KHz that are the actual cause for the audible differences
(probably the issue with Geoff Emerick console), and because the
differences heard are just in the listener's mind, what is know as
expectation effects or placebo effect, and the cause for the need of
double-blind listening procedures in any reliable test worth that
name.

Human hearing limits and auditory mechanisms are pretty well known
today. IIRC, according to the very knowledgeable Jim Johnson (JJ)
from ATT Labs, one of the fathers of MP3 and AAC algorithms, the
human hear works basically as a group of resonators in paralel,
followed by an envelope detector. This knowledge has made possible
the development and actual working of those psychoacoustic lossy
compression schemes, that in case of good quality algorithms and
implementations, allow for a bitrate reduction down to 1/6 of the
original without *any* audible difference in 99.9% of cases.

To believe that pure tone testing discloses the extent of
human hearing is to believe that the ear/brain is limited to
sinusoidal detection and discrimination. This has not been
proven by any means. It's rather like saying that the
discriminatory power of the eye could be disclosed by
measuring its response to featureless monochromatic
sources. There is as yet no reason to believe that the
ear/brain doesn't do other things like edge or feature
detection or wavelet like decomposition which may not be
triggered by sinusoids. In an evolutionary sense, the
production of sinusoidal stimuli is a _very_ recent
development and I have to wonder why the ear/brain would be
particularly sensitive to them other than as a side effect.
That organ evolved in an environment of much more spectrally
complex stimuli and is more than likely to have evolved
means for detecting those natural stimuli which may well not
respond to a pure component of their spectrum.

With music I know for certain that I can hear effects of
equalization in the spectral region beyond that where I can
detect tones.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

From: lvaro Jos Rego <alvreg@...>

hi to all, Im from brazil. a legend, or reality...
** A 48 input console had been delivered to George Martin's Air Studios, and Geoff Emerick was very unhappy about it. It was a new console, made not long after I had sold the Neve company in 1977. George Martin called me and said, "please come and make Geoff happy, while he's unhappy we can't do any work".
They'd had engineers from the company there, and so on. The danger is
that if you are not sensitive to people like Geoff Emerick, and you don't respect them for what they have done, then you are not going to listen to them.
Unfortunately, there was a breed of young engineers in the company (I
hasten to say this was after I sold it !) who couldn't understand what he was bitching about. So they went back to the company and just made a report saying the customer was mad and there wasn't really a problem. Leave it alone, forget it, the problem will go away. They were acting like used car salesmen. I was very angry with it. So I went and spent time there, at George Martin's request, and Geoff finally managed to show me what it was that he could hear, and then I began to hear it, too.
Now Geoff was The Golden Ears and he still is and he was perceiving
something that I wasnt looking for. And it wasn't until I had spent some time with him, as it were, being lead by him through the sounds, that I began to pick up what he was listening to. And once I'd heard it, oh yes, then I knew what he was talking about. We measured it and found that in three out of the full 48 channels, the output transformers had not been correctly terminated and were producing a 3dB rise at 54kHz. And so people said, 'oh no, he can't possibly hear that'. But when we corrected that problem, and it was only one capacitor that had to be added to each of those three channels, I mean, Geoff's face just lit up ! **

Go here and listen to this sound sample:


That's a little grass frog recorded in the old .AU format with a sample rate of 8kHZ. Then go listen to the true sound of this frog:

Recorded in mp3 format but at 44kHZ sample rate.

The thing to note is that the little grass frog has a very intense call, but at about 7.5kHZ. I can hear this frog while driving down the road at 55mph. At a sample rate of 8kHZ, not a bit of the original call was there. But there is still sound, at a much lower frequency. This is a fairly crude example, but is part of a common problem. A/D tend to have cutoff filters just to keep them from producing odd stuff from the higher frequencies. I have no idea what their sound setup was. I do know that every frog that has sound components above 4kHZ on their site has a messed up recording.

High frequencies can produce effects in lower frequency ranges. And I'd be certain that's what Geoff and you were actually hearing. Otherwise you would be bothered by the very loud location and hunting calls of bats. Do you hear bats clearly? Many of them are lower frequency than 54kHZ. And bats are pretty much everywhere. And there are a whole range of small mammals, insects and so on that call in these frequencies, sometimes quite loudly.

Golden Ears does not change human physiology. This error in the wiring had other effects in the regular frequency range that Geoff's fine tuning to how equipment performs detected. And to show it was a learned thing and not a function of the ears themselves, he could teach you. Are your ears Golden? I doubt it, and neither are Geoff's. What's golden with him is his mind. If you like the sound he likes. I doubt that a hearing test on Geoff would show anything unusual.

Note that I've given the Savannah River site folks notice that they are not providing the calls of the Little Grass Frog, but some electronic derivative several times. Over a number of years. Some folks are hard to convince. That sound has been on the internet on their site for at least 7 years.

Walt
wwknapp@...

I would like to make some binaural mics for my DV camcorder (Canon
DV60) as an experiment. I am sure the thing doesn't supply power to
the mic input jack, so I am assuming I'll need to use the battery
supply as shown on the MicDYIers web page to go along with the home
made mic pair they show there. Is this correct?
I realize this is beneath most of you but I am new to this recording
stuff, though an avid electronics experimenter.
Thanks in advance, Kyle....

hi to all, I?m from brazil.



a legend, or reality...


** A 48 input console had been delivered to George Martin's Air
Studios, and Geoff Emerick was very unhappy about it. It was a new
console, made not long after I had sold the Neve company in 1977.
George Martin called me and said, "please come and make Geoff happy,
while he's unhappy we can't do any work".

They'd had engineers from the company there, and so on. The danger is
that if you are not sensitive to people like Geoff Emerick, and you
don't respect them for what they have done, then you are not going to
listen to them.
Unfortunately, there was a breed of young engineers in the company (I
hasten to say this was after I sold it !) who couldn't understand
what he was bitching about. So they went back to the company and just
made a report saying the customer was mad and there wasn't really a
problem. Leave it alone, forget it, the problem will go away. They
were acting like used car salesmen. I was very angry with it. So I
went and spent time there, at George Martin's request, and Geoff
finally managed to show me what it was that he could hear, and then I
began to hear it, too.

Now Geoff was The Golden Ears ?and he still is and he was perceiving
something that I wasn?t looking for. And it wasn't until I had spent
some time with him, as it were, being lead by him through the sounds,
that I began to pick up what he was listening to. And once I'd heard
it, oh yes, then I knew what he was talking about. We measured it and
found that in three out of the full 48 channels, the output
transformers had not been correctly terminated and were producing a
3dB rise at 54kHz. And so people said, 'oh no, he can't possibly hear
that'. But when we corrected that problem, and it was only one
capacitor that had to be added to each of those three channels, I
mean, Geoff's face just lit up ! **



best regards


álvaro j r

_______________________________________

I am done using 12VDC to 110VAC power inverters for field audio
recording. If at all possible stay at DC voltages. Some equipment
built for wall-warts actually work fine on DC. I don't know a Digi
002 at all.

The problem with square wave inverters was that it worked fine until
the dew started to set in.
Then multiple ground loop problems surfaced and were severe. Many
paths and even high quality mic cable was not immune as it bled from
battery ground to shield.

We ended up having to hang a battery by rope to a tree.

Rich

--- In micbuilders@..., "Palazzo Enrico" <hharpa@t...>
wrote:

Look to some kind of inverter designed for powering laptop

computers by car battery.

Bye
Enrico
----- Original Message -----
From: Jason May
To: micbuilders@...
Sent: Sunday, December 14, 2003 4:34 AM
Subject: [micbuilders] Portable power


Hi all, I am looking for a portable power setup to power a digi

002 and

mic preamp in the feild. Any suggestions?

thanks,

Jason



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system ().
Version: 6.0.550 / Virus Database: 342 - Release Date: 09/12/2003

Look to some kind of inverter designed for powering laptop computers by car battery.
Bye
Enrico

don't even start on golden ears and speaker cables


--- In micbuilders@..., "grendeltooth" <grendeltooth@y...>
wrote:

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

Hi all, I am looking for a portable power setup to power a digi 002 and mic preamp in the feild. Any suggestions?



thanks,
Jason

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@...

From: ognelson@...

Hey all--
This reminded me of a question I meant to ask long ago: is the response/performance/accuracy of a mic/diaphragm affected by lots of use at high spl's over time, as the diaphragms in my ears have been? I've been recording a lot of loud concerts for years with a pair of Core Sound omnis, and I sometimes think I'm hearing a change in the quality of the recordings. The thing is, my ears have suffered from decades of loud music, engine rooms, guns, etc., so that might be what I'm hearing. There are also the variables of room, PA, battery box battery life, etc. to account for. (I wish I'd understood the effects of lound noises when I was a young rocker--I always wear hearing protection now that it's too late!)
So, do mics lose their youthful hearing as they age?
Olaf

I don't think diaphragms are stressed over their elastic limits even by such high levels.

Diaphragms will be more changed by what they pick up from the air. One biggie is being around smokers, but there are plenty of other sources. Note that diaphragms can change with age. A lot depends on the exact composition of the film. Generally this results in a less elastic diaphragm, which can also be due to environmental contaminants as well. But all of it is really not due to the level of sound they have recorded. Some people choose specific older mics just for whatever aging has done to them.

I have a pair of Sennheiser MKH-110's installed in a Modified SASS. Those are probably about 40 years old more or less. Their sound quality compares very favorably with a pair of MKH-20's that are near new in another Modified SASS. In fact the differences are probably exactly as they would be if both pairs were new. So mics can last a long time if built well.

Note that the MKH-110 was originally put out as a instrumentation mic. For picking up sound from things like engines on test stands, etc. It is especially unique in it's low frequency pickup. The standard version is rated down to 1HZ, there was a variant rated down to 0.1HZ. A lot of the difference I hear in the MKH-110 vs the MKH-20 is how much better it does at reproducing low frequency detail compared to the MKH-20, which is not at all bad at it. The high frequency performance of the MKH-110 does not differ that much from the MKH-20 to my mind. Though that's the end where you would expect aging to be most evident. There is enough difference between the two that I usually have both along. And you can be sure that when I find a nice bunch of frogs calling in a thunderstorm it will be the MKH-110 I'll grab.

Remember, even the sounds the bands put out have changed over the years. To my mind they put out lower quality sound.

It would be likely that your ear damage is a lot of the change in how you hear these things. And, of course your own attitudes change how you hear things. Your brain accommodates those in interpreting the signals from your ears, it does not give you just the raw data. If, over that time period, you have become more discriminating about sound quality your brain will modify it's interpretations to accommodate that. You'll hear those flaws in the recording that your brain ignored back then. If you have the older recordings in unmodified form go back and see if they still sound the same.

I have tried to protect my hearing all my life. But the tests are clear, I don't hear the high frequencies near as well as I once did. Even if you protect your ears perfectly, just age will change them. Sigh...

Walt
wwknapp@...