How would a trumpet sound without its harmonics past 20khz

[Howard, D and Angus, J]

Right, to gather up all of these questions:

Timbre is a remarkably complex subject, and all that people have mentioned here are some different aspects of it. After a bit of searching around, I managed to find a pdf document that summarises the research - it doesn't go into all of the detail, but certainly identifies the true scope of it. For the full detail, you need access to the research documents, and generally they're only available on subscription. An explanation about the number of harmonics you need to correctly identfy and distinguish timbres is contained in Howard, D and Angus, J Acoustics and Paychoacoustics (2 ed) Focal Press 2001 ISBN 0 240 51609 5 and this is a recommended book. In essence, it suggests, I think quite correctly, that since humans with a limited hearing range (up to 16kHz) can accurately determine the timbre, and therefore type of an instrument without any problems at all, then extended harmonics cannot possibly be neccessary for the purpose.

Phase is certainly an issue when you are generating harmonics, and certainly arises as an issue in timbre, but it becomes a lot cloudier when you look at it in terms of human perception and acoustic conditions. I think that for all practical purposes, you might as well say that phase distortion and phase error are intimately related, except that clearly, one will cause the other!

Just to play the devil's advocate:

 

   
In other words, it is what we cannot hear that is sometimes important.

   
Yes, inside an instrument as a part of the timbre generation process within the human hearing range, but not the way you are suggesting, I'm afraid.

And:

 you would know that the non-linearities involved in mixing these sounds (where Helmholtz comes into this isn't clear) give rise to harmonics within the audible spectrum that are able to be perceived by the human ear.

If you take it all together, then suppose that some of the very high harmonics used in creating the sound of the trumpet are emited by the bell (100% conversion would be rare). Okay, they are very directional and short traveling, but with an extended mic well placed you could capture them.

BUT: loudspeakers are very non-linear systems! Wouldn't those higher frequencies (while being part of the sound emmited by the trumpet, but not being part of its "sound") create "new" down-converted frequencies -within the perceivable range- that are harmonic related to the trumpet. So it would sound different, but not as intended! You would be generating distortion by this.

Don't know if I made myself clear. The idea is that by capturing ultrasonic frequencies that are emmited by the instrument, and reproducing those by a non-linear system, you are in fact adding distortion to the whole. As this distortion may be within the audioband, it will change the sound. It is too easy to use this changed sound and label it an "improvement" without understanding what is going on. In fact, it may be a deterioration.

And now I'm running for cover while Steve lines up the big guns........

And now I'm running for cover while Steve lines up the big guns........

No, I think that this is all probably true. But why anybody would want to record a trumpet from a position in which nobody would ever comfortably listen to it is beyond me! If you want to make a reasonable recording of a trumpet, and you want to be able to reproduce it in a similar way to which it is normally heard, why would you want to artificially add extra harmonics to the naturally generated ones?

There was a crazy guy years ago who decided to record an organ by placing a microphone in the Swellbox (I hope he was insured!), and the results sounded dreadful, by all accounts. He thought that he was recording a more accurate version of what the pipes sounded like. Maybe he was, but what he did certainly didn't sound like the organbuilder's intention of what the instrument should sound like, or anybody else's, for that matter.

But certainly, the basic premise is correct - you just have to ask yourself why anybody in their right mind would want to do it!

But why anybody would want to record a trumpet from a position in which nobody would ever comfortably listen to it

A few months ago there was a very similar remark in Sound-On-Sound about recording a French horn. The point was that everybody seems to be wanting to record it from behind, where the bell points. While the intention of the instrument itself is that is should point backward and be listened to from the front. So you should record it from the front with maybe something to help the reflections a bit behind it.

I think it all fits in the current craze of close-micing everything in pursuit of absolute isolation and definition. Sometimes it is done so blunt it gets on my nerves. Some examples:
- guitar recordings where you hear so much string slapping against the frets you begin to ask if you are listening to a beginner. And this is supposed to be an "audiophile" recording.
- piano recordings where you hear more of the hammers and dampers than the pianist itself.
- violins that are so scratchy your hairs come straight and not from the emotion of the music.
- organ recordings without any natural acoustics.
- clarinet/sax/etc where you can count the clappets.
And this only in the classical music. In pop/rock I can understand it as the philosophy of the "sound" is different but even then: a drum kit is an instrument in itself, not 10 separate ones. If the drummer cannot balance the parts of its own instrument it might be time to look for another drummer.

AAAARHGggggg! Have these engineers/producer ever gone to a concert? OR am I getting too old?

A few months ago there was a very similar remark in Sound-On-Sound about recording a French horn. The point was that everybody seems to be wanting to record it from behind, where the bell points. While the intention of the instrument itself is that is should point backward and be listened to from the front. So you should record it from the front with maybe something to help the reflections a bit behind it.

Yes, I read that too...

AAAARHGggggg! Have these engineers/producer ever gone to a concert? OR am I getting too old?

Presumably they've gone to the one they're recording? But common sense flees the moment they get in the door with 45 microphones, invariably. Mind you, it can go the other way sometimes as well - I have a 'recording' made in the amazingly reverberant acoustic of St Ouen in Rouen, France where the (insert your own expletive) who made it used two omnis well back in the nave to record the organ. And the resulting mess may just as well not have been issued. It's a shame, because the performance wallowing around in there wasn't bad, as far as I can tell.

Maybe with max compression being the must_follow standard, these newer microphone techniques at least add back a bit of individuality and differentiation?

Maybe with max compression being the must_follow standard, these newer microphone techniques at least add back a bit of individuality and differentiation?

Individually crafted distortion, eh?

That link on timbre is too technical for me.
I need a timbre for dummies book or something.
And those formulas (my God) anything with a sigma or delta in it makes me start to run.

John Cage staked out his turf. A lot of people looking for themselves somewhere have to try something else.

That link on timbre is too technical for me.
I need a timbre for dummies book or something.
And those formulas (my God) anything with a sigma or delta in it makes me start to run.

Well, the book I mentioned is a little easier to understand, but it also has formulae. Unfortunately, the subject is complex - and if you also consider that our brains can ascertain almost instantly what instruments we are listening to in an ensemble, even if we've never heard those particular examples before, you have to conclude that there is a significant degree of brain processing going on as well - both in pattern recognition and stimulus sorting terms. It's difficult to research, and the more people discover about this, the more they realise that they don't actually know. In fact the brain processing parts of timbre really are a bit of a mystery - but we can say that we know what the limits of the information available are, because this is measurable, and external to the brain function, being provided by what amounts to no more than an adaptive transducer (AKA the ear).

But even if you don't understand all of the overview article, it certainly gives you an indication of how many factors there are involved, doesn't it?

I'd like to say thanks steve for the information you've provided it's been a great help.

Without it's harmonics above XXkHz. the trumpet sound should have less total energy though, right?  So maybe this is where/if we detect the difference - the intensity of impulses within the envelope, not the sharpness after a point, but the integrated sum of each impulse still, which adds level to our perception at that point and below.  

If the increased perception is of level alone then you can turn up the volume a bit to get the same result.

If the increased perception of level is near/at the highest perceived frequency you can do the same thing with a treble EQ curve of some kind.

A microphone should act much like this and simply get louder at frequencies it can reproduce when hit with an impulse that includes higher frequencies.  If so then you can record this ultra-sonic effect and reproduce it with normal recording equipment now at 20kHz.

The next test might be to remove level from the comparison by normalizing the files, or remove EQ by EQ matching, and see if people can still tell a difference.

Without it's harmonics above XXkHz. the trumpet sound should have less total energy though, right?  So maybe this is where/if we detect the difference - the intensity of impulses within the envelope, not the sharpness after a point, but the integrated sum of each impulse still, which adds level to our perception at that point and below.  

If the increased perception is of level alone then you can turn up the volume a bit to get the same result.

If the increased perception of level is near/at the highest perceived frequency you can do the same thing with a treble EQ curve of some kind.

A microphone should act much like this and simply get louder at frequencies it can reproduce when hit with an impulse that includes higher frequencies.  If so then you can record this ultra-sonic effect and reproduce it with normal recording equipment now at 20kHz.

The next test might be to remove level from the comparison by normalizing the files, or remove EQ by EQ matching, and see if people can still tell a difference.

The end of the trumpet moving sideways less than an inch in front of the microphone will make more difference than any of these 'tests' will. In terms of achieving anything useful, you have to keep your feet on the ground with something like this - and now it's just getting silly... go and re-read the stuff about directionality.

Quite correct Steve about directionality, but you may have missed my point.      The trumpet got in the way Im afraid.

I'm thinking hypothetically and generaly of coarse, about the question of ulta-harmics on CD, playing the devils advocate and giving the benefit of the doubt to the golden ears that can hear the difference between ultra-harmonics in vs. out.  
For those people the effect is either real or a placebo effect.  

I realize this could only be measured with carefully controlled a/b conditions, such as comparing recorded materials.  Perhaps i should have indicated how slight this difference in level must be, assuming there is a subjecvtive difference at all.  

Certainly worth a test, and relatively easy with good test mic and monitors with response to >25kHz., if only to eliminate this possible means of detection of those ultra-harmonics.    

The only silly thing here would be to talk/read about it more, when a simple experiment will suffice.  This is what i propose.

So to clearify, let's assume the trumpet is on a fixed stand with controlled air flow etc., or better yet let us assume we are comparing two otherwise identical wav file playbacks, the original and a copy that's missing the frequencies above 20khz.

If it's a tiny increase in level that they are detecting, then they can turn up their volume a tiny bit and be happy, and we can dispense with ultra-harmonics on CDs etc. forever.  That should make everyone a lot happier except the consumer audio manufacturers.

[the same]

Well i had to check this theory out with a primitive experiment and...      

After trying this out using CEP/AA by creating some tone and harmonics files i find that you can put a lot of ultra-sonic harmonics onto a tone without perceiving any level increase.  I used a sine tone at 3kHz. and then intermittantly muted the first five or so harmonics and i could hear the extra highs clearly switch in and out with both ears, giving a fuller sound.

When i did the same thing with a 5kHz. fundimental i could hear no increase in level in my ear that's only good up to about 10kHz., even though there was an increase of 6db in level each time the harmonics were switched in!       I guess there is no subjective increase if you can't hear the harmonics!  Oh well, good to know.  

My good ear could hear the extra sound as fuller if not louder, but the inconsistant effects of high frequencies was already quite apparent, and can only get worse for people who can hear above 20kHz.

This does suggest then that people will not hear any increase in level, or any other difference for that matter, with the inclusion of harmonics above ones hearing ability.    [just a study of one though using tones not impulses]

Update:  unfiltered 48kHz. impulses seemed no louder than impulses with 10kHz. on up filtered out with fft filter.  There was a hefty 8db more level on the unfiltered impulse yet i heard no difference in level or timbre of the tick while switching the filter on/off.      the 8db is off the output meters so i better make sure it is still 8db out of the monitors and into my ears.  
OK update > the Studio Projects c1 mic and/or my monitor steeply rolls off starting at 15kHz. - it's almost -6db down at 22kHz.

Conclusion:  OK the test stands for the bad ear and the impulses were possibly only only 2-4db instead of 8db as stated and extended to 15kHz. only, so it stands at 3db at least.

For the purposes of recording - Answer to the posted question: the same.