M0013744 Speaking or conversation tube
Credit: Wellcome Library, London. Wellcome Images
images@wellcome.ac.uk
http://wellcomeimages.org
Used by the very deaf to obviate the need for the close approach of the speaker if the trumpet type of hearing aid is used.
Photograph
Early 19th century Published: –

Copyrighted work available under Creative Commons Attribution only licence CC BY 2.0 http://creativecommons.org/licenses/by/2.0/

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