On the bass and cello (and probably violin and viola as well), it seems like many aspects of proper form serve the purpose of getting ones arm over the left shoulder to play high on the fingerboard. So, are there any instruments that have been built with the left shoulder made concave?
If there haven't, is it just a chance thing that no one has thought of it or felt the need for it, or are there acoustic reasons to keep the instrument roughly symmetrical?
As far as double basses are concerned, it's not uncommon to see a body with something like this:
Just a normal double bass body, with a left shoulder cutaway (if it is really called like that). They are used to help the player on the higher positions. One company (that comes to mind) that makes such basses is Framus :
I understand why you ask such a question, and for a beginner it would make the playing in higher positions easier, but (speaking as a double bassist), you just get used to the "traditional" built of it.
Aside from electric instruments like @Aaron mentioned, this is not unheard of but extremely rare. I have seen a few upright basses over the years in bass shops with a cutout in the upper bout like this or even more pronounced.
I even found a pic of a viola with a similar feature:
I have never seen this on an acoustic cello or violin but I would not be surprised if there are some out there.
My take (and personal experience) is string players are used to and even rely on where the body meets the neck for physical cues on where to find upper register notes. Because of this most players prefer a symmetrical instrument. Even electric string instruments usually have some type of abbreviated shoulder because string players are used to a transition from neck to body.
As for acoustical properties, I cannot say for sure but changing the shape and symmetry of an instrument will probably have at least a minimal effect on the sound.
The "electric family" of string instruments are often designed without any shoulders. The below photos come from Wikipedia's entries for electric cello and electric upright bass, and an internet search will show you lots of other designs -- much in the way that electric guitars can be shaped in myriad ways.
For acoustic instruments, one consequence of eliminating a shoulder is that it would reduce the resonant surface area of the instrument.
To really get into the nitty-gritty on this, you could find a copy of The Cambridge Companion to the Cello. Chapter 3 is devoted to cello acoustics.
There is also the extensive "Acoustical Studies on the Flat-backed and Round-backed Double Bass," which, while examining a different property of the instrument, may offer some relevant insight.
an electric cello
an electric bass
It's hard to imagine a violin/viola player having a problem with the shoulder of the instrument, even with the worst posture imaginable. The arm, in particular, just doesn't touch the instrument. The smaller size of the instrument means that even the highest note on the fingerboard can be reached by just reaching the hand across. I don't have my own video of this, but if you search for "violin highest note" you can find many examples. In reality even that isn't likely to be a problem since the very high notes are hard to play for other reasons.
Posture for violin/viola is more a product of:
And a few optional but handy things:
There are some alternative positions that miss 4 and 5, such as holding it like a cello or the Indian position where the player sits on the floor and the top of the instrument is braced on the player's foot, but even with those variations 1-3 really limit the options.
