Complex sentence: The very earliest mechanical telephones were based on sound transmission through pipes or other physical media, and among the earliest known experiments were those conducted by the British physicist and polymath Robert Hooke from 1664 to 1685.
Split into simpler sentences: The very earliest mechanical telephones were based on sound transmission through pipes or other physical media. Among the earliest known experiments were those conducted by the British physicist and polymath Robert Hooke from 1664 to 1685.