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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...

and

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:-)

Alexandre Eremenko
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    The diary of Samuel Pepys says “August 8th, 1666. Discoursed with Mr. Hooke, whom I met in the streete, about the nature of sounds, and he did make me understand the nature of musicall sounds made by strings, mighty prettily; and told me that having come to a certain number of vibrations proper to make any tone, he is able to tell how many strokes a fly makes with her wings (those flies that hum in their flying) by the note that it answers to in musique, during their flying.” So it was no later than that. “Mr. Hooke” here is of course Robert Hooke, first secretary of the Royal Society. – Mark Dominus Nov 14 '14 at 14:49
  • @MJD: This was later than Mersenne whom I mentioned, but thanks for the wonderful reference! – Alexandre Eremenko Nov 14 '14 at 17:56

2 Answers2

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Is there any evidence that this relation between sound and oscillations was known in antiquity?

It doesn't appear that the ancients had any proof that sound waves were oscillations in a medium, although Aristotle appears to have been the first to theorize about it. From this pdf (with a transcript available here):

The wave interpretation was also consistent with Aristotle's (384-322 B.C.) statement to the effect that air motion is generated by a source, "thrusting forward in like manner the adjoining air, to that the sound travels unaltered in quality as far as the disturbance of the air manages to reach."

This "wave interpretation" is a reference to later ideas by Vetruvius and Chrysippus. Earlier, however, Boethius proposed something similar.

This gives very similar text:

One of the first references of sound as a wave is found in a statement made by Aristotle where he indicated that air motion is generated by a source, trusting forward so that the sound travels unaltered in quality as far as the disturbance in the air manages to reach.

However, it doesn't seem like there were any experiments done in antiquity to confirm or disprove these theories. For this, we have to go to Robert Boyle (quoted from the previous source listed):

Robert Boyle's classic 1660 experiment on the sound radiation by a ticking watch in a partially evacuated glass vessel provided evidence that air is necessary, either for the production or transmission of sound.

Wikiquote gives this passage from Vitruvius's The Ten Books on Architecture:

Voice is a flowing breath of air, perceptible to the hearing by contact. It moves in an endless number of circular rounds, like the innumerably increasing circular waves which appear when a stone is thrown into smooth water, and which keep on spreading indefinitely from the centre unless interrupted by narrow limits, or by some obstruction which prevents such waves from reaching their end in due formation. When they are interrupted by obstructions, the first waves, flowing back, break up the formation of those which follow.

This text can be found on page 139 here.

HDE 226868
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The concept of oscillation in air conveying sound did not develop all at once, but was instead a natural development of ancient ideas.

Aristotle, for example, may have had a correct understanding of sound, thinking of the vibration of (say) the string of a musical instrument, causing a similar vibration in the air, this being received with a similar vibration in the ear of the listener.

In his work On the Soul, he writes about the nature of sound propagation. Sound, he says is conveyed by "the air originally struck by the impinging body and set in movement by it".

It is rightly said that an empty space plays the chief part in the production of hearing, for what people mean by 'the vacuum' is the air, which is what causes hearing, when that air is set in movement as one continuous mass; but owing to its friability it emits no sound, being dissipated by impinging upon any surface which is not smooth.

It is the friability of air that he comes back to repeatedly, the ability of air to be "broken down" into smaller parts by motion or friction. This, to me, suggests something like how a wave compresses and rarifies very small portions of the air.

Joe
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  • You are right. Put is shortly: the vibrations of a sting we can not only hear but also see. This is confirmed by what the sources I just found say. – Alexandre Eremenko Nov 14 '14 at 00:46
  • +1 for a good answer and a primary source. – HDE 226868 Nov 14 '14 at 00:52
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    I have no knowledge of this aspect of Aristotle's wrok, but that quotation does not suggest periodicity to me. The movement of "one continuous mass" applies to a rock sliding down a hill better than it applies to periodic compression and decompression. (It's worth noting that Aristotle is notoriously tricky to translate, so a different translation might give a very different impression of this passage.) – Mars Nov 14 '14 at 02:00