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I'm reading a book called "Telephony" published in 1905 (Miller,Mcmeen).
The book starts with this quote:

To properly understand the manner in which sound is transmitted from one end of an electric circuit to the other, it will be necessary to entirely get rid of a popular idea, and to fix clearly in mind, that the sound produced at one end of a circuit actually travels over that circuit, in order to be heard at the other end.That is erroneous; in reality the actual sound produced at one end of the circuit, travels no farther than it would if the telephone apparatus were not present. What actually take palce instead may be described as follows: The sound energy produced in the presence of the telephone apparatus is transformed by the apparatus in electric energy, which, traveling to the distant end of the line, is again retransformed by the distant apparatus into sound energy.

I don't understand the point.
What is the misconception they're trying to address?

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At least as I read it, he states the misconception fairly clearly:

the sound produced at one end of a circuit actually travels over that circuit, in order to be heard at the other end.

His point is that the sound at one end of the circuit is converted to electrical signals by the microphone, then that resulting electricity travels through the circuit, and at the other end, sound is produced based on those electrical signals.

Yes, to most of us today, that probably seems pretty obvious--but in 1905 it wasn't nearly as widely understood. It appears that a fair number of people originally thought of the phone system as a more elaborate version of the old "telephone" kids made with a string between two tin cans.

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That, of course, is not accurate at all.

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  • \$\begingroup\$ In 1905, the electrical signals that were sent and received would have been analogs of the local sound pressure. Impulses (i.e., digital signals) came much later. \$\endgroup\$ – Phil Freedenberg Jul 7 '19 at 15:09
  • \$\begingroup\$ @PhilFreedenberg: Analog signals are impulses too, especially analogs of speech. \$\endgroup\$ – Jerry Coffin Jul 7 '19 at 15:13
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I think the clue might be in "published in 1905". The electric telephone was radically different to the speaking tube which was popular in the previous century (and still has applications now).

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Figure 1. A 19th century speaking tube. Science Photo.

The article is merely pointing out that there is an acoustic-electric interface at the microphone and an electric-acoustic interface at the earpiece. The audio is transmitted electrically in between.

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