Evaluating a violin’s tone.
There is no accepted way of evaluating the tone of a fiddle: everyone, including me, has their own idea of what a fiddle should sound like! I bet that helps. But it also depends on what you want to do with it: a bluegrass fiddle needs to be quite brash to be heard over the banjo and various guitars - but is probably not suited to classical at all. A chamber instrument (for quartets etc). needs to be responsive and intimate or it can be overpowering.
Squawkers and squeakers.
Well, there’s a lot of squawkers and squeakers out there among the cheap violins .......... so we do need some way of assessing them with fact rather than opinion.
More objective methods.
A simple way of checking to see how even a violin or viola is across all the strings there is a simple method first used in the early 20th Century before oscilloscopes and computers. It is described in various books on the physics of music, and it’s easy and quick to do these days. You just play every semitone from the bottom G open string upwards as loudly and evenly as possible while recording the violin. Here is an extract from Alex. Woods “The Physics of Violins” (1944) showing response curves for strads. and other violins using this method.
Ideally a sound level meter should be used with the whole experiment done in in an anechoic chamber [no echo’s from the walls etc], but a mic and a well-damped room or workshop will do. Here’s how Carleen M Hutchings describes it, and shows what an ideal (i.e a Stradivarius) violin response should look like, and where the key 3 resonances should be. Open strings tend to sound overly loud (see below) so it’s better to use 3rd position for the D, A and E strings.
Play each note for about 1 second standing say 2 feet from the computer’s microphone. Leave a gap of say one second between each note: a silence. You can even say out loud the note’s name, it helps.
Then on the playback waveform, select each note with the mouse and read off the (rough) RMS* amplitude measured in dB, from the meter in Audacity. (It did work better with ‘professional’ software such as ‘Cool Edit 2000’ however, where the RMS energy can be read off the selected waveform using Analyze => Statistics, directly in dB) **.
I then plot the response using these figures (dB, vertical scale, uncalibrated) for each semitone using a logarithmic horizontal frequency scale so that equal octaves are equal distances on the x-axis. Note that I used open strings (D, A, E) which therefore appear about 2dB louder than other notes.
You can see that the response of a fiddle, even a strad., varies by some 10 dB, or about a 10 times ratio of sound power max. between various notes over its range. This seems to be a lot, but this is also where the instruments tone colour comes from too.
What does this tell us?
Well, if you’ve paid $20 k for a fiddle it tells you whether the maker got the fundamentals of the physics right. Note that Carleen was not impressed by the “Peter Guarnerius” of her example, but how a fiddle responds to attack of the bow is more than just how loud it is.
This fiddle example is showing less response for ‘G’s, while similarly 2 other fiddles I’ve plotted responses for show less output on ‘D’s. So we can use this technique to find out or to confirm our impressions of a fiddle’s strengths and weaknesses, and put numbers to them. That helps, especially in suggesting what to change and do in the next fiddle!
* RMS = root mean square: a measure of the total energy in a sound wave.
** Select say 500 -1000 mS of waveform, and 0dB = FS [Full Scale] sinewave.