John Laurie and his colleagues carry out tests on telephones to check their clarity. London.
Telephone tests at the Post Office Engineering Research Station to determine the percentage of words received correctly.
Dollis Hill, London.
M/S of John Laurie at table talking into microphone. M/S speaker on the wall. M/S man at desk with headphones on taking down messages. C/U girl wearing headphones, camera pans down to notes she is taking. Various shots of John at table taking telephone off stand and fixing another one on. C/U John's face. Various shots of telephone on stand, C/U as John checks adjustments on phone. C/U John's face. C/U code words used in the testing of the phones. C/U as John begins to talk again. C/U sound meter with needle moving. C/U chart and man writing on it, the camera pans up to the man who is wearing headphones. C/U headphones.