Timbre

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AudioArtist
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Timbre

Post by AudioArtist » Tue Apr 12, 2011 5:07 am

Timbre- The quality of a musical note, sound, or tone that distinguishes the sound of different voices or instruments.
The most obvious factors that influence the timbre of different instruments are construction, materials, and size.
The timbre of a sound is the result of it's harmonic content. A good way to illustrate this is with one note played on a certain instrument.
I promise this is the only math I'll use here and it's sooo simple. If you play A4 on a piano, it's fundamental frequency is 440hz. The subsequent primary harmonics are all additions of the fundamental frequency value so, F being the fundamental frequency and F1 and F2 are the resulting harmonics we get this,
F=440hz, F1=880hz, F2=1320hz, F3=1760hz and so on... Any harmonics below the fundamental frequency will be partial or incidental harmonics. More on this later.
The apparent volume/power of these harmonics is what determines your harmonic content.
Now let's look at how these harmonics are balanced when playing a pure tone with synth waveforms. Sorry for the fuzzy pic. Notice how the triangle and square waves have more content across the harmonics. Also note that the first harmonic is less prominent than the second. This chart is somewhat misleading in regard to the sine wave, there are harmonics they're just nowhere near as prominent as the square and triangle waves.
harmonic structure.JPG
There are many partial harmonics apparent as well but for now and for the sake of simplicity let's just say that they are naturally occuring as well as influenced and in some cases produced by the construction, materials, and size of the instrument.
So any one instrument will have it's own unique distribution of harmonics across the entire audible spectrum.
So in the simplest way of describing it, that is Timbre.
Here is a chart which shows the fundamental frequency ranges of several different instruments.
instrument freq chart.jpg
I also highly recomend The Master Handbook of Accoustics as reading material, it covers timbre in depth and much much more.
So feel free to amend, add to or delete this. And any questions that I am able to answer I will.
-Gabriel-
Last edited by AudioArtist on Wed Apr 13, 2011 7:52 pm, edited 2 times in total.

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Cfgk24
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Re: Timbre

Post by Cfgk24 » Tue Apr 12, 2011 6:41 am

Thankyou Gabriel - Good article.

I like to think of 'Timbre' as the 'Colour' of a note. This is something that as korg ds10 players - we have an incredible amount of control over. We can make a note sound hugely different without even changing the pitch.
Using a simple toy electronic keyboard, you will have no control over the TImbre, a Professional standard Piano will have a lot wider range of TImbre depending on Pedal use and attack and release of the keys.
Violin players have a huge amount of Timbral range. But nothing beats a true Synth.
Timbre is the reason why a good soloists Violin cuts through and can be heard above the rest of the Orchestra - it is for this reason that some violins have such high monetary values (stradivarius for example).

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Re: Timbre

Post by AudioArtist » Tue Apr 12, 2011 6:56 am

Thanks cfgk24! Timbre is often refered to as tone quality or tone colour. Your example of the stradivarius violin is a perfect illustration of how no two instruments are alike, even if they are both constructed of the same materials in the same dimensions. Even two strad. violins will be different.
I tried to keep this article as simple as possible, however there is alot more ground to cover. Hopefully this new sub-forum will inspire some good discussions. Great idea BTW!

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Re: Timbre

Post by AudioArtist » Wed Apr 13, 2011 7:14 pm

I must appologize to you all. I mistakenly confused my harmonics with my octaves. I'm editing my original post to correct the math and the frequency values of the harmonics. The difference is subtle but it makes a hugely significant difference. Again, I'm very very sorry, I feel terrible about it. Please look over it again to see the correct info.
Next up will be a short description of the partial and incidental harmonics and maybe a little on complex waveforms.
Last edited by AudioArtist on Wed Apr 13, 2011 8:15 pm, edited 1 time in total.

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Syscrusher
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Re: Timbre

Post by Syscrusher » Wed Apr 13, 2011 7:30 pm

Thanks AudioArtist! The description of harmonics will come in handy when we start talking about triads!

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Re: Timbre

Post by AudioArtist » Thu Apr 14, 2011 3:49 am

Timbre - part 2 - partial and incidental harmonics

Partial Harmonics- partial harmonics are harmonics which share no mathematical relation to the fundamental frequency. Partial Harmonics are spread across the entire audible spectrum at seemingly random intervals. However, there is an explanation for this phenomenon.
In reference to the original post, The most obvious factors that influence the timbre of different instruments are construction, materials, and size.
Take two different guitars as an example. One is built from solid birch wood, and the other from solid mahogany.
The factor we need to focus on is the density of these different woods. Birch is a less dense yet more resonant wood. Mahogany is a more dense but more mellow wood in terms of produced sound.
You could take both of these theoretical guitars and play an A note on them and you would yield different results when viewing them on a cathode ray ocsilliscope or a digital spectrum anylyzer.
The guitar built from birch would have more harmonic content well above the fundamental frequency because it is a more resonant wood. The Mahogany guitar would have more harmonics centered near the fundamental because of it's density.
Both guitars, however, would produce many harmonics which would not mathematically relate to the fundamental frequency.
The reason for this includes not only the wood, but, What type of glue was used? How thick is the wood?, How many internal braces were employed in the construction? ect.
Those questions and many more variables beyond can apply to almost any instrument. Thus, it's easy to see how many variables affect the timbre of any given instrument.
Incidental Harmonics- Here we open the can of worms. Any instrument will produce sounds that are not necessarily intended. Let's use violin as an example. At certain points even the most skilled violin players will create high pitched screeching noises. While these can sometimes be appropriate and even pleasing it is an artifact or anomaly in regard to purely perfect violin playing. These 'unwanted' sounds on a violin are centered rather high in the audible spectrum. So the harmonics generated by these notes can reach well beyond the human range of hearing and the partials below can reach way down into the range that only an excellent subwoofer could handle. Go figure, a violin rockin your sub!
Another good example would be the typical palm mute metal guitar chunka chunka. The palm muting effectively deadens the resonance of the strings and as a result creates an odd low end rumble because notes are unable to resolve and you get a kind of crashing of waveforms in a disharmonic fashion which creates an unusual low end sound.
Well that's enough for now. The next topic will be complex waveforms and I'll bring things back to where it relates more to the DS-10.
-Gabriel-

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