Sound is an oscillation of a medium (waves in the medium), and the frequency of thse oscillations we hear as the pitch.
When this was discovered and by what experiment?
I suppose this was already known to Marin Mersenne (whose book was published in 1637)
I know what simple experiment can prove this. It is the so-called "syrene", but the earliest descriptions of this device that I now are of 19-th century. Though there is nothing in it which Hero of Alexandia could not understand or invent.
So my question splits into several warts:
Is there any evidence that this relation between sound and oscillations was known in antiquity?
If not, when this was discovered, and what experiment was used. The source that I have says:
The interpretation of sound as a vibration also goes back to antiquity, although its more precise expression waited early-modern mechanical philosophy...
In the seventeenth century, Galileo Galilei and Marin Mersenne popularized the correspondence between pitch and frequency that Giovanni Battista Benedetti, Galileo's father Vincenzo, and Isaac Beeckman had earlier articulated. Accordingly, a musical tone is a periodic succession of pulses transmitted by the air to the eardrum
but it gives no reference on "antiquity".
EDIT. Thanks to those who answered. I just found the following "cite" in an acoustic book:
Pythagoras (570–497 bce) observed that “air motion generated by a vibrating body sounding a single musical note is also vibratory and of the same frequency as the body;”
But the author does NOT give the source of this sentence in quotation marks!
If this is correct, than the most ancient exact science is acoustics, not astronomy, as we all thought:-)