What is Diaphanoscope?

Diaphanoscope definition and meaning on Dictionary terms:
a foghorn producing a low-pitched, penetrating signal of two tones.
Phonetics. a phoneme in one dialect corresponding to a similar but phonetically different phoneme in a related dialect. a group of sounds comprising all the phonetically different dialectal variants of a given phoneme in a language: The broad a and flat a of a??halfa?? are members of a single diaphone.


reference: https://www.dictionary.com/browse/diaphanoscope