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Article : Timbre

"The Timbre"
By Bill Barret

Bill About ten years ago I did alot of experimenting at the speech pathology
labof a local hospital. they let me use all kinds of amazing equipment
(spectrometers,state of the art recording equipment, complex computer
analysis programs on sound and aerodynamics etc...).

I had a bunch of my favorite local harmonica players come down and blow
into various gadgets with the same and different harmonicas much to their
amusement. The results were cataloged and analyzed and with the help of two speech pathologists I came up with statistical models to discuss tone production and the harmonica.

It was a lot of work, and at the end of it all I felt like I knew less then
when I started. It did help me develop the ability to distinguish between various timbres better, and gave me a vocabulary to discuss it but... ultimately what I really wanted to do was improve my own tone, and the research wasn't helping. I gave up.

When it was all said and done I never finished the scientific paper. I did write a small essay on what I learned for other musicians. most of which was honestly pretty boring. i'd like to include a mercifully abreviated version of that anyway, and use it as a launching point for understanding and working on Tone production.

the more important experiences i've had regarding tone have been personal experiences as an enthusiastic listener, and player. all of the time spent at the speech lab paled compared to one day of actual street performing on a windy peer, or an evening on stage trying to get more out of my amp & mic
technique, so as to be heard over the din of the local guitar neanderthal.

Anyway, here it is-


Timbre, is

It's the character that differentiates between tones with the same frequency and volume.

Most of us know intuitively what timbre is. we've heard a difference in our own sound as we switch from one harmonica to another. we've also heard a difference between our "sound" and another players sound playing the same harmonica. The first time I really experienced the latter was during a lesson from
Eddie Manson. I thought my harmonica was having problems. he took it from me a played one
long beautiful note, then a quick major scale and handed it back to me. I couldn't believe it was my harp. I was demoralized, but inspired.

Timbre is a complex topic. So "it is the character that differentiates between two notes of the same frequency and amplitude" great, but what does that mean. let's break it down a little.

There is a difference between amplitude and loudness. Amplitude is a measure of sound pressure which is a quantity, a physical attribute. Loudness is a quality, a perceptual attribute. loudness is measured in
Bells. a tenth of a bell is a decibel. it takes three more decibels to make the sound twice as loud, three less decibels and the sound is half as loud.

The same is true with frequency and pitch. That is, frequency is a quantity, a physical attribute, and pitch is a quality, a perceptual attribute.

Furthermore, loudness differs with pitch. We hear middle frequencies better than low and high ones of the same amplitude. "So far there hasn't been any strong evolutionary pressure to hear a really bithcin' bass groove. While middle frequencies 'Grok! Run" saber tooth tiger ! Waga waga!", have been very useful" -Dave Moulton (home recording magazine).

Let's simplify and discuss timbre only in relation to it's physical attributes. All other things being equal two notes with different timbre will have a different "spectra". One short note on the harmonica is actually a complex tone made up of many simple tones of various frequencies and amplitudes. These simple tones are called "partials" or "harmonics" (if they occur at regular intervals), they are called "noise" (if they do
not). These can be viewed with a Spectrograph.

These two attributes of the timbre, it's SPECTRA and HARMONICS TO NOISE RATIO, although important, are not the only attributes. there is one other worthy of mention FORMANTS.

A formant is a boost, a hump in the spectra at a place that has nothing to do with the fundemaental. a guitar has a large formant made by its body. Some instruments have no formant, an oboe for example. whether formants exist on the harmonica remains to be seen.

For the purpose of brevity i'll limit the discussion to acoustic tone. "Acoustic" tone is the sound just you and your harp make before you step up to the Microphone. that is, prior to it being processed by any transducer (a microphone or pickup) and turned into an electronic signal. ELECTRIC tone is what occurs after the transducer.

I think of acoustic tone as divided into three systems:
1) the vocal tract,
2) the harmonica,
3) the hands
(or coffee cup etc...) should you choose to use them (it).
Let's take a closer look at each of these.

The VOCAL TRACT is a 10 cm, flexible tube, capable of an infinite number of subtle variations in shape an and volume. In speech the noise generator (larynx) is located at the beginning of the system, the back of your throat. The harmonica's noise generator is at the opposite end of the system. With speaking, and singing the formants are the throat and sinuses. Their size and shape give your voice a different and often shifting timbre. With harmonica the same is true but the role of formants is a much less dramatic and less misunderstood.

The HARMONICA itself is a free reed instrument. It consists of a comb, reed plates, reeds, cover plates, and if it's a chromatic, it also has slide, cursed windsavers and a slide mechanism. In the last few years there has been a lot of experimenting and discussion here. It's lead to a great deal of clarification and controversy. I'm certain that there is little can add to the discussion that talented harmonica
customizers and bright mechanical engineers haven't already covered. I recommend searching the Harp-l archives for the role each part of the harmonica plays in timbre.

I have noticed that different harmonicas sound differently to my ears when I play them. Also, I can say that they had different spectra, and harmonics to noise ratios when I checked them out with the spectrograph. whether that's the size of the reed plates, or the material the cover plates are made of
etc... I honestly don't know. I just have my treasured opinions.

The HANDS play a huge role in shaping timbre. "They are to the harp as stops are to the organ " according to my mentor Eddie Manson. I believe they are undoubtedly the biggest and most ignored tool in shaping the acoustic tone.

To get an idea of how exaggerated you can change the timbre with this system (your hands) listen to the aforementioned Mr. Mansons version of "The Polka" by Shostokovich (the little fugitive suite -Folkways), or for subtlety, listen to "Joey's Theme" on the same LP. For that matter listen to anything by Tom Ball. each solo is a lesson in depth and blues history.


Bill Barrett can be reached at:
P.O. Box 642590
Los Angeles, CA 90064