3

When I play the G string on my violin exceptionally softly, among the sympathetic overtones I hear is a diminished fifth. Why is this? Is this specific to my particular instrument? Out of curiosity, I tried this on another (cheap) violin and I didn’t hear it.

dalearn
  • 233
  • 1
  • 7
  • 4
    It would be GREAT if you could record this for us. – Bob Broadley Mar 12 '20 at 00:07
  • @BobBroadley I would but I’m not sure that my phone’s crappy mic could pick it up. It’s very very soft. – dalearn Mar 12 '20 at 01:19
  • 5
    You mean the **open** G-string? Maybe you need to tune your D string!!! – Old Brixtonian Mar 12 '20 at 01:19
  • 1
    Anything would help. It’s certainly intriguing, the b5 not being prominent in the harmonic series! – Bob Broadley Mar 12 '20 at 01:20
  • 1
    I think Old Brixtonian may well have hit the nail on the head here...! – Bob Broadley Mar 12 '20 at 01:21
  • Do you hear the flattened fifth above the open G, or somewhere high up among the other harmonics? – Old Brixtonian Mar 12 '20 at 01:22
  • @OldBrixtonian Nope, it’s in tune. For what it’s worth though, those two strings are noticeably sensitive to tuning. It’s very hard to get it just right. – dalearn Mar 12 '20 at 01:22
  • But do you mean it's only when playing the OPEN string? or does it track what you play? – Old Brixtonian Mar 12 '20 at 01:24
  • @OldBrixtonian Interesting question. It’s definitely higher up but I don’t have the ability to tell how much higher it is. – dalearn Mar 12 '20 at 01:24
  • @OldBrixtonian I noticed it on the open string and didn’t think to check others. I’ll check when I have access to my instrument tomorrow. – dalearn Mar 12 '20 at 01:26
  • Interesting question. – Old Brixtonian Mar 12 '20 at 01:28
  • 4
    Simple solution to narrow it down: play that string while muting the other three. See (hear) what happens. – Tim Mar 12 '20 at 07:38
  • 1
    What you're probably hearing is the 11th partial tone, which sounds very like a tritone in a higher octave. It may seem relatively prominent because it's the first partial that is really, really dissonant when judged by classical harmony principles. – Kilian Foth Mar 12 '20 at 09:08
  • @KilianFoth - but one can learn to love the eleventh partial. https://soundcloud.com/scott-wallace-189088488/cauliflower – Scott Wallace Mar 12 '20 at 09:33
  • @ScottWallace Indeed. Olivier Messiaen even claimed that his predilection for ending melodic lines with tritones had this exact reason. – Kilian Foth Mar 12 '20 at 10:44
  • 1
    Unless you can back this up with an FFT of a recording, it's most likely you aren't hearing exactly what you think you are hearing. – Carl Witthoft Mar 12 '20 at 15:07
  • 1
    For those of you who were interested, I do hear the ringing when I play other Gs, not just the open string. – dalearn Mar 13 '20 at 01:57

2 Answers2

5

Your ear could be off.

Even though the dim 5th is NOT an overtone of any vibrational frequency based on the standard accepted model of a string, there are a couple things that could cause this.

  1. The response of the other strings to an input is not an ideal response right at resonance. All naturally occurring system have damping and this broadens the response cure. Ideally the response of a system at resonance is infinite and rapidly diminishes off resonance. When damping is present a system can respond off resonance with a relatively noticeable response relative to that on resonance. The peak response will still be on resonance but the neighboring frequencies will have a good response as well.

  2. The ideal string model with integer harmonics, fn = n*f1, is not that accurate. Strings behave like very thin beams with boundary conditions depending on thickness and tension. The frequency spectrum of a stiff beam can have non integer harmonics, in one case the augmented 5th comes out. I've recorded this using a very low pitch tuning fork and analyzed. The overtones matched the theory fairly well. You are stating dim 5th and the case I am mentioning is a +5 but it is possible that for your soft driving force the violin string is not behaving like a perfect string but has some other physics in it. This phenomenon can be heard in pianos for some notes, usually at the high end of the piano.

  3. A combination of the two concepts mentioned above but applied to the body rather than the strings. The body parts act more like plates with boundary conditions and these do not have integer harmonics. They can have all sorts of resonance modes with irrational ratios to the fundamental and exhibit stiffness as well as flexibility. This along with damping could be causing a plate harmonic to get excited by the string and driving force of the bow.

Also, it could be a red herring. But if you are interested in learning more about overtones in instruments that are not idea you can find this is several books by Fletcher and Rossing. They are fairly well known in the field of acoustics (either physics or engineering) and have spent their lives researching the physics of musical instruments. Some of their books are very dense with math but they do have a few that provide a survey of the facts without derivations.

Let us know what you find out.

2

I suggest letting a luthier check out your instrument. The reason can be the string itself, it can be the position of the sound post just to mention two possibilities, there could probably be many other possible reasons, so you don't know what it is until you get a proper check of the violin.

Lars Peter Schultz
  • 4,272
  • 1
  • 6
  • 20