From what date can we trace the knowledge (or the hypothesis) that sound has a finite speed of transmission through air? Thunder/lightning is the most striking clue, but echoes would be the readiest source of controlled observation. However, I would appreciate some historical data.

Speed of travel is implicit in the idea that sound is transmitted via oscillations - which are discussed in some useful answers to this question, so perhaps there is not much more to be said, but I am particularly interested in the simpler idea that sound travels with a finite speed.

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    $\begingroup$ When firearms were invented and spread. This is completely evident to a person who sees and than hears a gunshot at a distance. But oince you understand that lightning and thunder come from the same source, you can also make this conclusion. $\endgroup$ – Alexandre Eremenko May 7 '15 at 1:55

The question is delicate because of the phrasing that assumes empirical approach, which did not emerge until 17th century. And the notion of "speed" as applied to sound presupposes the concept of wave in a medium, which dates to late Renaissance. The use of "speed" in antiquity was mostly confined to uniform motions of localized objects, not light or sound.

But the idea that sound takes time to travel is ancient if not prehistoric. The earliest surviving written record is perhaps Aristotle's Meteorology (c.334 BC), where he gives his theory of thunder and lightning: "...the dry exhalation that gets trapped when the air is in the process of colliding is forcibly ejected as the clouds condense and in its course strikes the surrounding clouds, and the noise caused by the impact is what we call thunder... the ejected wind burns with a fine and gentle fire and it is then what we call lightning, which occurs when the falling wind appears to us to be coloured. Lightning is produced after the impact and so later than thunder, but it appears to us to precede it because we see the flash before we hear the noise." (boldface mine)

General theory of sound is described in Aristotle's De Anima, but he mostly elaborates on what was a consensus among Greek natural philosophers since early pre-Socratics: sound is some kind of movement of air (with each part "striking the air which is next to it"), and no movement can be instantaneous because the same thing can not be two places at once. This was suggested by experience with noisy falls and hits, vibrating strings and air filled pipes in musical instruments, etc. The collision theory of thunder relies on such intuitions, and goes back to Anaximander (c. 611-547 BC) and Anaximenes (c. 585-528 BC). According to Aristotle, Empedocles (c.450 BC) even thought of light as "traveling or being at any given moment between the earth and its envelope, its movement being unobservable to us". On this account Aristotle disagrees because he considers light a state rather than a movement. But on sound there was complete agreement, I am not aware of anyone who thought that sound spreads instantaneously.

However, nothing resembling the expression "finite speed" was used anywhere in antiquity to describe either light or sound. Leonardo is credited with suggesting c.1500 that sound travels in waves in the modern sense ("we see the waves running across the field while the grain remains in place"). This allows one to make sense of speed and frequency. However, first measurements of the speed of sound were only attempted in 1630s by Mersenne and Gassendi, the first "authoritative" one was the one performed by the Florentine Academy in 1660.

  • $\begingroup$ thank you @Conifold, a very useful and informative discussion. $\endgroup$ – David Holden May 6 '15 at 23:06

I'm not sure if there was ever a doubt that sound has a finite speed. Your reference to thunder/lightning may have allowed people throughout history to realize that sound has a finite speed, slower than light.

It was Ole Roemer who first discovered that light traveled at a finite speed, people before him believed that light traveled at an infinite speed. Article about Ole Roemer

Back to the sound question, while it may have been intuitive for people to realize that sound travels slower than light, Pierre Gassendi was the first known person to try to measure the speed of sound. He got the speed wrong, but did figure out that the speed is not dependent on frequency. His experiments used cannon fire, observing the difference between the flash and the sound at a known distance. He did assume that light was traveling at infinite speed when performing his calculations. Here's an article about him in general, with only a small bit about the cannon experiments.

Large article about Pierre Gassendi

Also, Aristotle posited that the speed of sound was dependent on frequency. Gassendi had religious/philosophical issues with Aristotle's views, and one reason for the sound experiments was to prove Aristotle incorrect.

More on that at www.encyclopedia.com/topic/Pierre_Gassendi.aspx

  • $\begingroup$ thx Steve. a + for the useful refs. i didn't realize the frequency dependency hypothesis is to be found in Aristotle. even if wrong that seems a relatively sophisticated idea for the time - one might look for the reason to adopt it without evidence, unless it fitted with some other preconception - do you know what the reason for this was? $\endgroup$ – David Holden May 6 '15 at 19:05
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    $\begingroup$ @David Holden Aristotle had no concept of sound "frequency", let alone "speed of sound" depending on it. He talks of air "falling upon and striking the air which is next to it", and is too vague to make sense of either the frequency or the speed. Those require concept of a wave, which came much later. And although Roemer was first to measure the speed of light successfully people suggested that light takes time to travel centuries before him. Aristotle mentions Empedocles, Avicenna and Alhazen also held such view. $\endgroup$ – Conifold May 6 '15 at 20:51
  • $\begingroup$ @Conifold and SteveMichaelson, I've asked the follow-up question Did Aristotle suggest that different kinds of sound might travel at different speeds? for some clarification. $\endgroup$ – uhoh Jul 15 '17 at 7:41

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