Roelof Vermeulen at Philips : a search for space in music

Roelof Vermeulen's career at Philips started in 1923 and ended with his retirement in 1959. He developed a stand-alone loudspeaker for Philips' first radio receiver in 1925 and was the driving force behind many developments in the field of electroacoustics. Despite the high sound quality for their time achieved by Philips radios of the 1920s and 1930s, according to Vermeulen, the reproduction of music through a single loudspeaker remained a serious limitation: monaural sound offered the listener not more than a virtual hole in the wall of the space in which the music was performed. While the introduction of stereophony was an improvement, in the sense that the location of the instruments in the performance space now became perceptible and their diverse soundcolours better distinguishable, something essential was still missing from the musical experience, namely the experience of the performance space itself. Experiments with artificial head microphones for binaural recordings and with stereophonic recording were therefore soon expanded with so-called ambiophony; a technique developed by Vermeulen whereby loudspeakers reproducing stereo sound were supplemented with indirectly oriented speakers for "diffuse" sound. Out of the desire accurately to record and reproduce the acoustical properties of a musical performance space evolved a new ambition: to use electroacoustic means to vary those properties in the concert hall in real-time. Stereo reverberation devices for this purpose, already developed by Philips in the 1950s, were in use in numerous theatres and concert halls, for example in the Teatro alla Scala in Milan, and found further application in the production and performance of electronic music.