harmonics in violin strings

Question

a friend of mine is playing violin, and she explained to me that she can hear if she plays a false note because the string doesn't resonate well

i find it very counter intuitive based on what i know of physics and harmonics (very few actually), i would have think that when she pull the string at one point, it "creates" a new string, shorter than the whole one, and with it's own harmonics. So, whatever the size of this substring is, it should sound well (I'm not speaking relatively to the other notes of the music, but the note on its own)

instead, she showed me that if she pull a random point on the chord, and play the string, when we listen carefully we can hear the sound beeing kind of empty, or rough (sorry i never speak of music in english, i don't have the vocabulary). Instead, when she plays one of the notes of the tonality, the string sounds better, it's like there are more harmonics in it

how is it possible ? it's an electric violin so it has little or nothing to do with the "box". Does that means that you cannot tune your violin to whatever tonality you want ? like instead of a C, you would want something a quarter tone above, it would sound bad ?

Answer 1

Since it is an electric violin, what you're hearing is likely sympathetic resonance with the other strings through the bridge. This effect is taken advantage of by the Hardanger fiddle, which uses sympathetic strings strung underneath the main playing strings.

You could test this by tuning the other strings down a semi tone and see if that changes the "in tune" sound of the fingered notes on the in tune string.

Answer 2

I think you're right to be suspicious of this idea! For a start, if we're talking single notes, there's no such thing as a 'false note' in absolute terms - Each reference pitch and temperament of a given fixed-note scale will have a given set of 'true notes', and every pitch would be 'true' for some combinations of scale, reference pitch and temperament.

If you are confident that you did observe a strong difference, then as per Tom's comment, one explanation might be sympathetic resonance with other strings. Even then, those resonances wouldn't necessarily create a pattern of 'true' notes, for the aforementioned reason that what's 'true' depends on the reference pitch and temperament. If you're supposed to be playing in equal temperament, string resonances will lure you astray.

Of course resonances of the 'box' are another possibility, but perhaps you're right that that's not a consideration on an electric violin. You might be hearing resonances of the bigger 'box' - the room you're listening in!

The tone of a real-world string does change as it is stopped to shorter lengths, because of things like the width becoming proportionally greater compared to the length, although you'd expect that to be a progressive effect as you move up the string.

Another possibility is that your friend simply has a good sense of pitch and plays more strongly and confidently when she knows she's in tune!

Answer 3

There are several ways to intonate a note on a violin. A basic way of intonation is to listen to the "ringing" notes. That is the notes which resonates with the open strings. An example: play a D on the A string (third finger on the A string). If that note is exactly one octave above the open D string it has a resonance which violin players call a "ringing" sound. If you play it slightly flat or sharp the "ring" or resonance disappears. The note D also gets resonance from the G string provided you have tuned the violin in pure fifths. It is called Pythagorean intonation.

As far as I can see that is what the OP is talking about in this question. So what I wrote above is the answer to the question, but since I mentioned that there are several ways to intonate a note on a violin I think it is fair to elaborate on that.

Therefore here is an elaboration on other ways of intonating on a violin:

Expressive intonation which is playing the sharps very sharp and the flats very flat. That is typically done when playing leading notes, like a very sharp C♯ leading up to D. Another way of expressive intonation is playing blue notes in blues really blue. You can play them as blue as you want.

Then there is "just intonation" when playing double stops. Like play a C♯ on the A string together with the open E string. Then you will realize that this C♯ needs to be slightly flat in order to get a well sounding third in just intonation. As opposed to the C♯ you would play as a leading note up to D.

There is also equal temperament (ET). This is typically done if you play in unison with a piano.

A violin player usually plays with a mixture of those types of intonation.