What is an overtone?

[Pitar]

An overt one is a person who displays transparency. An over tone is an indirectly initiated sympathetic frequency modulated by another frequency in modulation.

One string plucked places others in motion and the chorus of tones generated are described as over tones.

[Tico]

Originally Posted by Pitar

An overt one is a person who displays transparency. An over tone is an indirectly initiated sympathetic frequency modulated by another frequency in modulation.

One string plucked places others in motion and the chorus of tones generated are described as over tones.

Nope.

Take all other 5 strings off.
Pluck the one remaining string.
Feed, via mic, into spectrum analyzer.
You'll see energy at all the overtones in the harmonic series of that string's fundamental.
This can only be untrue if the guitar's string could produce a pure sine wave which has no overtones only the fundamental; it can't.

That said, yes, two pitches sounded at the same time ALSO produces mathematical multiples overtones of them 'mixing'.
For example if one strings is tuned to 1000Hz and another at 2000 Hz each will produce overtones in their respective individual harmonic series.
BUT next you will also get an overtone at 3000 Hz (the sum of the two) and a series of overtones based on 3000 Hz

[Fattymagoo]

Originally Posted by Tico

Nope.

Take all other 5 strings off.
Pluck the one remaining string.
Feed, via mic, into spectrum analyzer.
You'll see energy at all the overtones in the harmonic series of that string's fundamental.
This can only be untrue if the guitar's string could produce a pure sine wave which has no overtones only the fundamental; it can't.

That said, yes, two pitches sounded at the same time ALSO produces mathematical multiples overtones of them 'mixing'.
For example if one strings is tuned to 1000Hz and another at 2000 Hz each will produce overtones in their respective individual harmonic series.
BUT next you will also get 3000 Hz (the sum of the two) and a harmonic series based on that.

Agree 100%

This is why percussive instruments (isn't guitar technically a percussive instrument as well?) also exhibit overtones ringing out. Or a hand clap, or boot stomp, as previously mentioned. Certain things lend themselves to producing more audibly perceptible overtones... Like rosewood over mahogany for example.

[Desafinado]

Originally Posted by brianmay

In view of the thread complaining about rosewood's overtones, it became clear to me that I didn't have a clue what the OP was talking about despite playing guitar since 1964 (quite badly probably).

My two guitars are both Sitka Spruce tops and EIR back and sides.

Serious question: What is an overtone (in the guitar context)?

Great thread and I thank the OP for it. We all talk about it, but...

[vindibona1]

Originally Posted by Tico

Overtone is the same in guitar context as in any other context.

Everything vibrates strongest (loudest) at its main resonance, aka fundamental frequency.
It also vibrates an octave above that.
Also, at a fifth above that octave.
Next, at a fourth above that.
Next, at a major third above that ... on and on to infinity.
It's called the natural harmonic series.

As overtones go up in frequency they get lower in volume, and an untrained ear probably won't notice them.

Harmonic is another word for overtone.

Now that you have the basic idea of "overtones" based on Tico's explanation, there is a second part of the discussion that should ensue...


RESULTANT HARMONICS:

When you play a single note, the "tone" is comprised of the fundamental and to a less extent the overtones as Tico described. But if you play a second note, there may be a sympathetic vibration that occurs between the two notes and cause overtones, or harmonics, from other notes to sound to greater or lesser extents. And without getting deeper into detail, the strength of resultant harmonics have largely to do with the intonation of both the fundamentals of both notes, but the intonation of the harmonics as well. Fully in-tun resultant harmonics create additional fullness and volume of sound without increasing the volume of the fundamentals.

I tried to keep it simple and will stop here. Hope I added to the discussion.

[Tico]

This is a display from a spectrum analyzer showing a series of overtones from an instrument playing ONE note at 147 Hz.
Note how overtones generally get lower in volume (lower on the chart) as you go up in frequency (to the right of the chart).
(Sorry the bottom got cut off, it says "Frequency (Hz)".)

The relative amplitude (height) of each overtone is what our brains decodes to identify the instrument, ie. flute vs. trumpet.
It even holds the sonic code of whether the instrument is made of metal or wood.
... even what guitar strings are made of, metal, gut or nylon.

A flute sounds like a flute and not a clarinet because of the relative amplitude of these overtones.
If you had enough experience you may even be able to hear and identify the sound (actually the relative amplitude of the overtones) characteristic of a cheap nickel flute, a sterling silver plated one, a solid sterling silver one, a gold plated or a solid gold one, and of course a wooden flute.

But we don't need your ears.
Their complex ratio of overtone-amplitudes reveals their identity.
Again, like a fingerprint, overtone-amplitude rations identifies your voice vs. that of your four year old daughter, even when singing the exact same pitch and vowel.
Lastly, even individual instuments made of identical materials will not have identical sound (again, overtone-amplitude ratios).

With guitars, all other things being equal (which we all know is not possible), rosewood would have a characteristic set of overtone-amplitude ratios that differers from that of mahogany.
Even two pieces of RW from the same tree would not be identical, but there will be a similarity or a family of ratios that is characteristic of any tonewood.

Read this>
http://meandering-through-mathematic...struments.html

[JimmerO]

A lot of good description of what overtones are so far.

As far as guitars and other musical instruments they all have overtones. It's the blend of overtones at different volumes relative to each other (i.e. for a played note or chord) that give an instrument it's character or tonal "color". A tuning fork probably doesn't have many overtones so you're hearing mostly the fundamental pitch. Quite useful for tuning.

So when comparing a rosewood back and side guitar to a mahogany back and side guitar many people hear more emphasis on fundamental tones with the mahogany. The rosewood guitar is thought to have less emphasis on the fundamental tone and more on the overtones making notes less focused yet rich in overtones. I say, many people hear, because my explanation is a gross generalization. I'm sure not everyone hears it that way and not every mahogany or rosewood guitar sounds that way. But I think that's what this generalized sonic opinion of the two tone-woods is mostly about.

I've heard beautiful guitars made with both mahogany and rosewood but they do have different characters.

PS - I was writing this as Tico was posting the graph above my post. That's a great graphic that displays exactly what's being discussed.

[SantaCruzOMGuy]

Does anybody have clips of two different guitars one being fundamental in nature in the other being rich and overtones so we can listen to a contrast?

Sent from my SM-G930P using Tapatalk

[Brucebubs]

Originally Posted by SantaCruzOMGuy

Does anybody have clips of two different guitars one being fundamental in nature in the other being rich and overtones so we can listen to a contrast?

Sent from my SM-G930P using Tapatalk

I was just about to ask the same question.
As the owner of a rosewood jumbo 12-string I've got a sneaking suspicion that I'm an 'overtone' junkie.

[Tico]

Originally Posted by SantaCruzOMGuy

Does anybody have clips of two different guitars one being fundamental in nature in the other being rich and overtones so we can listen to a contrast?

Stuffing a guitar full of sox will suppress overtones more than the fundamental.

Sorry again ... okay, just shoot me.

[JeffreyAK]

The mix of harmonics varies between guitars, but also strongly depends on where the strings are picked. Pick near the neck, a lot more fundamental - pick near the saddles, a lot more harmonics. Electric guitars also throw pickup location into the mix, and tend to suppress harmonics with nodes near the pole pieces. Strings make a big difference too, bright vs. dark composition and coating differences. Complicated stuff, and a lot more complicated than just which wood the back and sides are made of.

[Howard Klepper]

Originally Posted by perttime

There's a couple of articles on wikipedia that might help:

https://en.wikipedia.org/wiki/Guitar...nics#Overtones
"When a guitar string is plucked normally, the ear tends to hear the fundamental frequency most prominently, but the overall sound is also colored by the presence of various overtones (integer multiples of the fundamental frequency). The fundamental frequency and its overtones are perceived by the listener as a single note; however, different combinations of overtones give rise to noticeably different overall tones (see timbre)"

Wikipedia and several posters on this thread are making a small, but significant mistake here. 'Harmonic' is not synonymous with 'overtone.' Harmonics are integer multiples of the fundamental frequency of the tone. But most of the overtones on non-electronic instruments are not harmonics, because their frequencies are not exactly at integer multiples, and can get a long way off from the ideal integer multiple.

This has nothing to do with equal temperament (a confusion in one of the posts above). In guitars and other stringed instruments it is because the overtones on real (as opposed to ideal) strings do not vibrate at the harmonic (integer multiple) frequencies--they vibrate sharp, and become increasing sharp as they go higher up the overtone series. This is called 'inharmonicity,' precisely because the overtones are not harmonic. And this causes a lot of the tuning problems in stringed instruments, but that's a topic for other threads.

All harmonics (beyond the fundamental, which can be called the first harmonic) are overtones, but not all overtones are harmonics.

Some posters have referred to sympathetic vibrations between strings and interactions of closely spaced tones known as 'difference tones' which can be internal to the ear/brain. These are not overtones.

So much for technicalities. Regarding rosewood and mahogany, it makes some sense to say rosewood guitars on average have stronger overtones, but that is really just another way of saying they are brighter, usually combined with their having long enough sustain that the overtones ring for a while. But I kind of cringe whn I see people say "rosewood has too many overtones." Woods don't "have" overtones. Musical tones do. Guitars that are played produce overtones, but what those guitars sound like result from many things other than what back and side woods they are made with.

[Wyllys]

It's the opposite of a covertone...

[robj144]

Originally Posted by Tico

Overtone is the same in guitar context as in any other context.

Everything vibrates strongest (loudest) at its main resonance, aka fundamental frequency.
It also vibrates an octave above that.
Also, at a fifth above that octave.
Next, at a fourth above that ... (aka 2 octaves above the fundamental)
Next, at a major third above that ... and on and on in smaller intervals to infinity.
It's called the harmonic series.

As overtones go up in frequency they get lower in volume, and an untrained ear probably won't notice them but everyone's brain decodes their loudness ratio to identify what the source of the sound is.

Harmonic is another word for overtone.

I just want to point out that higher harmonics do not necessarily decrease in amplitude as you go higher in frequency or order.

[robj144]

Originally Posted by fazool

I would be a little more specific.

Harmonic is the same as Octave. In vibration those are sometimes referred to as "orders", such as first order and second order - those are octaves.

Harmonics are usually octaves because they excite the easiest but "any" resonance can be a harmonic.

An overtone is when any other frequency becomes excited and elicited. Sometimes it is from aliasing, sometimes from straight orders.

Harmonics aren't really an octave. The fundamental to the first harmonic is an octave. The fundamental to the second harmonic is three octaves, yes, but the second to first harmonic is 3/2 which a fifth. I get what you're saying though.