Peter Brothers

“Several of the filmʼs key sound effects were accomplished musically, the most famous being the monsterʼs roars, which went beyond the sound departmentʼs capabilities.  Various animal noises were recorded and modified but nothing worked until Ifukube came to the rescue by using a contrabass (basically a large bass fiddle); however the only one in existence in all Japan was at the prestigious Tokyo Music Conservatoryʼs Music Department which was not about to loan-out their precious instrument for the purpose of making a monster movie.  So one night Ifukube “borrowedˮ it, removed its lowest string, then had pupil Sei Ikuno stroke the remaining strings with a coarse leather glove coated with resin.  The sound was then tape-recorded before being played backwards at a slower speed supplemented with echo-chamber mixing, and the different roars were achieved by changing the playback speeds, giving the monster a melodic quality (the sound of the monster using its radioactive ray was a sped-up cymbal roll).”
― Peter Brothers, Atomic Dreams and the Nuclear Nightmare: The Making of Godzilla