III Revised, bars 1-4 (Ensemble Insomnio, Muziekgebouw aan het IJ, 2013). Transcribed by listening to YouTube (update from 2019).
Note: after relistening I think the high Eb from bar 2 comes from a form of feedback, while the actually played note is a B, in line with the example below.
III Revised, bars 1-4 (Ensemble Modern). Transcription from the CD (update from 2019).
Notes: There was a writing error in bar 2 in previous editions, the Eb should be a B (that is quite obvious, I don't know how it got in).
The higher Bb and Ab in bar 3 may come from a scratch effect of the violinist making an effort of playing a sfz effect.
In 2025 I came across the original score, that is far more complex during these opening bars, to the point that I think Zappa initially wrote out a rhythmical experiment.
Some more about this in the next update.