[Trombone-l] Acoustics of brass instruments

Sat Jun 10 09:12:51 CDT 2006

I dunno. .somebody said they were going to put some sound (the clippers I 
think) on an occilloscope.  I have an alternative for any of you who have a 
modern digital audio recording program:

I just played back my recording of Urbie performing "Quadrabones" . . .one 
of the tunes I copied over from vinyl recently.  This went into Cubase 
because it is set up for easy dubbing, and recording.  I hit play in Cubase 
and started goofing with the screen showing the waveform.  Since I have a 
pretty powerful setup the screen updates in very much a "real time" type 
look and feel.  The screen can also be controlled in real time to shift the 
amount of waveform you want to look at in the screen.  There are grabbable 
sliders for this and for the amplitude. . so you can adjust the tops of 
waves to fill the screen.

Well, as we know this tune "Quadrabones" is relatively simple material with 
the two stereo tracks having either two trombones (all are Urbie) or one 
trombone.  Urbie played this as loud as is conceivably possible.  At times 
UG is up in the "strip paint off the walls" dynamic and it sounds great.

[NOTE: he VIBRATOS at this very, very loud level when it makes sense to do 
so. . .thus destroying the other hideous myth that nobody ever vibratos on 
held very loud notes. . .the great players do this regularly. . .listen 
carefully to the Basie bone players most great swing era players especially 
trumpeters. . .and of course Urbie]

Anyway by shifting the time frame of the graphic image going by for the digi 
audio you can create a very realistic Ocilloscope effect.  The wave forms 
are relatively smooth (a la sine wave) with the smooth bumps at the back 
that indicate to me that two or three pitches are being added together (most 
likely the first couple of harmonics).  Then, when Urb gets really, really 
loud (I looked at one note in particular in his first improv solo in the 
middle. . .it is really a "rip" sound and very loud) -- here you have a 
signal which looks like a sawtooth wavefront with another component taking 
over in the last half of the waveform.  The front is definitely saw tooth 
looking (I'm sure I once read that saw tooth patterns are used in sythesis 
for brass sounding voices) with the last half looking like a much softer set 
of either five times the fundamental or maybe five and ten times taken 
together.  This much softer material looks to me like it may be more box 
shaped thus quasi-square wave in shape.

So perhaps with a "lip reed" we have a situation where the sudden opening of 
a buzzed lip causes a quick spiking of sound energy with a more gradual 
rebound of the lip material producing the angle of the saw tooth.

Chris Tune

----- Original Message ----- 
From: "Wessner, John" <jwessner at towson.edu>
To: "Richardson,Timothy Mr. DAC USAG Franconia DPW" 
<timothy.a.richardson at us.army.mil>; "Daniel Pliskin" 
<daniel_pliskin at hotmail.com>; <TROMBONE-L at server5.samford.edu>
Sent: Friday, June 09, 2006 2:15 PM
Subject: Re: [Trombone-l] Acoustics of brass instruments

> Just to be appropriately nerdy also:  The square wave is the derivative of 
> the triangle wave.  Therefore it will have one higher power of the 
> harmonic in the coefficient.  1, 1/3, 1,5, 1/7 as opposed to 1, 1/9, 1/25, 
> 1/49.
> jw
>
> -----Original Message-----
> From: trombone-l-bounces at server5.samford.edu
> [mailto:trombone-l-bounces at server5.samford.edu]On Behalf Of Richardson,
> Timothy Mr. DAC USAG Franconia DPW
> Sent: Friday, June 09, 2006 1:44 AM
> To: Daniel Pliskin; TROMBONE-L at server5.samford.edu
> Subject: Re: [Trombone-l] Acoustics of brass instruments
>
>
> Out of pure-D nerdyness, I fired up a shareware tone generator last night
> and listened.
>
> A square wave sounds like a hair clippers.
>
> A sine wave sounds like a flute.
>
> A triangle wave sounds like a clarinet.
>
> Not that those tones could be mistaken for the actual instruments, of
> course, but there is some of the character in there.
>
> Now I'm wondering what a trio for hair clippers, flute, and clarinet would
> sound like.  You'd need a variable frequency drive to change pitch on the
> clippers, but these are so common on industrial equipment now that I'm 
> sure
> you could get one used for cheap.  I remember what I paid for the first 
> one
> I installed in a factory back in 1990, but the last one I put in was less
> than 10% of that cost, new.
>
> -----Original Message-----
> From: Richardson, Timothy Mr. DAC USAG Franconia DPW
> Sent: Thursday, June 08, 2006 08:04
> To: Daniel Pliskin; TROMBONE-L at server5.samford.edu
> Subject: Re: [Trombone-l] Acoustics of brass instruments
>
> Warning***Geek Hat on**********
>
> I think it is possible you've reversed the expansions for square and
> triangle.  Think about superimposing sets of sine waves to get something
> that looks like a square or triangle.  You're going to need lots more of 
> the
> lower harmonics to make it look like a square.
>
> Now that I think about it, you are right about a square wave sounding a
> little "clarinetty."  Most of the shareware tone generators can do sine 
> and
> square, and some of the drone tuning CDs are square wave based, so you can
> easily hear one.  I don't remember listening to a triangle wave since
> engineering school so I no longer have a clue, guess I need to find one.
>
> However, I did that hairclipper experiment, remember?  Fundamental 
> frequency
> was 50 Hz, which the trombone did not amplify.  There was no octave.  But 
> I
> could clearly hear a strong octave plus fifth, which would correspond to 
> 150
> Hz, the 3rd harmonic.   So I have to think square wave is correct.
>
> ********Geek Hat removed*************
>
> Musical story.  I live in a small farm village in central Germany.  The
> walls are foot thick stone, I live on a corner with no houses really 
> close;
> also most locals pull down rolladens at night.  I have assumed that I 
> could
> practise with impunity and probably nobody even knew I played trombone.
> However, this Saturday a band assembled outside my window at 5:00 AM, 
> played
> one tune, and departed.  I am wondering who I have p.o.'d.
>
>
>
> -----Original Message-----
> From: Daniel Pliskin [mailto:daniel_pliskin at hotmail.com]
> Sent: Wednesday, June 07, 2006 05:12
> To: TROMBONE-L at server5.samford.edu
> Subject: Re: [Trombone-l] Acoustics of brass instruments
>
>
>>We talked about the hairclipper
>>buzz recently.  That timbre indicates the waveform is a square wave.
>>We know intellectually a square wave is made up of a fundamental plus
>>odd harmonics, with the 3X frequency at 1/3 amplitude, the 5X at 1/5th,
> etc.
>
>
> My impression of a square wave is more clarinet-like.
>
> A hair clipper may well have only odd harmonics, but it sounds more like a
> triangle wave, which also has only odd harmonics, but if I remember
> correctly, the expansion is more like:
>
> fundamental/1 +third/3 + fifth/5 +...
>
> Where a square wave is something like:
>
> Fundamental/1 + third/9 + fifth/25 +...
>
> So the triangle wave has considerably more high harmonics.
>
> Of course, there are all sorts of duty cycle alterations, which also
> accentuate the higher harmonics.
>
> Some day when I'm really, really, really bored, I'll mike a hair chippers
> and check it out on an oscilloscope, for those inquiring minds out there.
>
> DanP
>
>
>
>
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