a user's mouth.

With Edison's megaphone, a low whisper could be heard a 300 m away, while a normal tone of voice could be heard roughly 3 km away. On the listening end, the receiver could hear a low whisper at 300 m. However the apparatus was much too large to be portable, limiting its use. George Prescott wrote: "The principal drawback at present is the large size of the apparatus."

Prior to the invention of the electric microphone, some early pop singers, such as Rudy Vallée, sang with

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