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Anders Buen

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About Anders Buen

  • Birthday 06/03/1970

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    Oslo, Norway
  • Interests
    Violin-, Hardanger- fiddle-, room- and architectural acoustics.

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  1. I do not know. I am interested in the measurement part of this. And to advice against conculsions about a better high frequency output from there, by using a mic under there.
  2. It will reflect from much lower frequencies than 8kHz. From around 3,4kHz at least. The room under the fingerboard is about 19cm long. The first resonance there between the bridge and neck heel comes at 900 Hz. The next comes at at 1800 Hz then 2,7 kHz and 3,6 kHz The neck heel end will be larger than its own surface because of the reflections from surfaces around. The reflection conditions are not ideal, but they cant be neglected, at least not in measurements.
  3. I do not think so. But if you put your mic under it there may be some difference. Remember the diemsnions of the ears the length of the ear canal and the enhanced sensitivity in the high frequencies.m They come from resonances in the ear canal. The size and shape of the ear helps to indentify the direction of the incoming sound together with the brain processing. If a midrophone had a curved fingerboard behind it near in a free field, I am sure it will influence the resulting recorded sound and spectra. A physical object start to diffract sound from wavelength/4 in dimension and reflect fully from about a wavelentgh dimension. 15cm of fingerboard is quite clearly visible to 15cm wavelength and shorter. With the mic between a fingerboard and a flat surface, we have a mic in a half open pipe due to the reflections. On a violin it becomes a bit more complex due to the curved top and taper. I think it bcomes more like a half open cone focussing in two directions. We would not record anything in such an environment, and it is impossible to draw any conclusions regarding the origin of sound. Even if the mic is outside of the fingerboard dimensions, there will still be influence from the under fb area. The sound generated there has to come out somewhere. And we can stil, «see» the underside of the fb in the top on each side near the fb.
  4. I think it can, and the main contribution is the bridge I think. There will be reflections and mirror sources there making the room bigger than we may think. The fingerboard also is curved making it focussing.
  5. Totally meaningless as everything matters. However ive read or heard one really great maker say that a good maker can make a good violin out of almost any wood. To make a great violin, takes great wood.
  6. There are of course connections between the properties of the body, the bass bar, setup and the high frequency response. I agree that it ios difficult to make both the low end and high end work well. If you can choose either both are pretty easy. The highs being more dependant on the bridge and setup. The thicker the top the pointier and clearer the «singers formant» in my experience and understanding, given a well fitted light and stiff bridge. Many modern makers, up until quite recently, made the plates and bodies too stiff, lacking punch in the low frequencies.
  7. It is known to be resonances in the cave inside, but not outside as I indicate. I mean under the fingerbord, above the top plate or including reflections from the top plate and the fingerboard. Any possible repetitive route there can become a resonance.
  8. There is no reason for more sound output under the fingerboard. However, there is a room between the top and the fingerboard, as well as between the bridge and the neck heel. There may build up resonances that appear as stronger sound radiation. Difficult to predict in detail, but the first axial resonance comes at 343/(2L) where the L is the distance between parallell surfaces. There are formulas for oblique resonances which may be related. The traveled path for the wave should meet the reflected one in phase to get a resonance. If they meet in antiphase, a weak spot will appear. Resonances appear for every whole number times the fundamental. E.g. the first mode between the neck heel and bridge comes at 900 Hz. The next one at 1800Hz and the third at about 2707 Hz in the region of interest. I have never seen anything on this before, it is an idea to explore. We do have an acoustic camera at work where such things might be able to be be investigated. I need a helper though, not easy in this summer holiday times.
  9. I agree that the "singers formant" is important. But it does not work well without proper stength of the fundamentals. A small violin may have plenty of the high frequency projecting sound, but will lack power. A singer with weak fundamentals and strong singers formant will sound somewhat like a "throut singer". A powerful and projecting violin need both. The same for a singer for large stages. Go back to the literature and get the whole picture. I think you can play with this both using filters in plugins for Audacity or in real life. Pick a children size violin for the test of lacking fundamentals or fill its f-holes with cotton.
  10. I think he had an early version of a spectrum analyzer he controlled using his foot and added the contribution from each harmonic manually. However, I do not understand completely how it was done. (I have copies of his articles so may figure out) The ISO equal loudness curves does not do all that much to violin sounds because the major part of the spectrum is in the flatter region of the relevant curve, which is a rather loud one for a player. A bit weaker one for a listener. In principle the curves will look much the same with and without such corrections.
  11. Sanders plots are quite unique being bowed instrument responses. The loudness given at a given note is the loudness you may expect while playing that noe. He played each half note as loud he could.
  12. I guess this is short term measurements, just after the stringing and some time after. Backs do distort over time, maybe mainly in humid periods. Tops do creep too and they move due to humidity variations. I am sure you have seen the measurements om the Cannon. Very small changes. Violins in normal non humidified conditions may see larger variation. Maybe mot comes above 50-60% but still. I wish we cold have some laser moire setup to see the changes at tension and humidity varation. A German researcher used some kind of "mosquito net" and lights to get iso-arch heights and photographed it. Maybe the method is sensitive enough for seeing small changes in arch shape from tension and humidity variations? Hermann Neugebauer und Gerhard Windischauer "3D-Fotos Alter Meistergeigen" Wölbunghöhen, etc, Verlag Erwin Bochinsky, Frankfurt, 1998
  13. Signature modes, or other modes, do react to excitation with the bridge foot in parallell too. Tapping the bridge straigt down does make sound..
  14. I can't find any by a fast read through of the discussion and conclusion. Rodgers and his co worker showed by FEA calculations of violin bodies that modes could move from changes of the arch shape. So that is my best guess.
  15. I was surprised to see how small changes they made. I would have thought it would be possible to change the lenght by 1-1,5mm maybe even 2mm. But I am a bit rusty now on this. Moisture content variation may give arch height changes of order mm. I wonder what typical soundpost summer and winter season length differences are in average.
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