the IPEM studio equipment


The skin of the drum vibrates, setting in motion the air around it. In no time at all the vibration reaches the listener's eardrum. The eardrum picks up the vibration pattern of the particles of air. The vibration signal is then converted into electrical signals destined for the brain. That grey matter recognizes the pattern as the vibrating of a drum. What type of drum may not be immediately clear, but it is certainly not a guitar. If we place a microphone next to the drum, the microphone membrane, like the human eardrum, picks up the vibration of the air triggered by the drum and converts it into electrical signals. This time, however, these electrical signals are not destined for the brain but for the amplifier, which makes the signal louder. Then the electricity is carried to the loudspeaker, which is simply a membrane that begins to vibrate. At this point the story begins all over again...

Thomas A. Edison was the first to turn the air particle movement into an analogue electrical signal, which enabled him to send voices round the world. By analogue we mean that the air pressure vibration and the electric vibration display the same pattern. This becomes clear when the pattern is visualized in a mathematical curve or graph. But whereas moving air quickly looses kinetic energy, that is not the case for electricity. Electrical signals move at almost the speed of light, and that is many, many times faster than that of sound through air. It is just that in the world of volts and amps different physical laws apply. That is why the distance between a transmitter and a receiver can be much greater than vibrations moving in the air. Transmitter and receiver need a transducer or converter to turn the moving air particles into electricity and vice versa. Microphones and loudspeakers are transducers.

As mentioned, an electrical signal can be strengthened, in other words the output of the second transducer (loudspeaker) can have a higher dynamic level than the input of the first transducer (microphone). But electrical signals can be processed in many other ways too. For example, a sound technician can filter certain tensions out of the current, thereby changing the sound which comes out of the loudspeaker. But more exotic phenomena such as morphing - literally allowing two signals to merge - also occur. The work of an electronic sound engineer might be compared to that of a sculptor; he sculpts a sound into the required form.

Electrical sound signals need not even be a transformation of an acoustic sound. A sound engineer can build synthetic or artificial electrical sound signals with generators. The best known and simplest synthetic form of sound is the sine tone, i.e. one simple, electric sine wave. The engaged signal on the telephone or the whistling that used to accompany the test card on the television are sine tones. In the 1940s, oscillators - for generating oscillatory electric currents - were used to build these sounds. In the case of radio stations in particular, they were part of the standard apparatus, for with the help of this pure sound, any interference in the ether could be detected. That is why the test card ("do the colours come out properly?") was accompanied by a test sound (is the sound pure?").  

The young Antwerp composer Karel Goeyvaerts (1923 - 1993) was absolutely fascinated by sine tones. Goeyvaerts believed that these pure waves could serve as basic elements for his music, as sound atoms. Whereas composers used to be given sounds, he wanted to compose sounds. In December 1952 Goeyvaerts wrote his first electronic score, which was no more than a diagram with instructions for a sound technician. As the National Institute for the Radio (NIR) turned a deaf ear to his experimental plans, Goeyvaerts looked to his best friend, the young Karlheinz Stockhausen. He managed to persuade him to start experimenting with electronic equipment at the Nordwestdeutsche Rundfunk (NWDR) in Cologne. Stockhausen was given access to the studios and in the summer of 1953 produced his 'Study I', a first, complete electronic tape composition. Synthetically generated and transformed sounds were recorded on a piece of PVC sound tape: resonate time, in other words, which was transformed into a tangible strip of a specific length. 

When such a tape containing carefully measured, combined and transformed electronic sounds was played in the concert hall, musical structures were heard which musicians cannot possibly perform. After all, the studio technician, who was the composer's equivalent, could work on each piece of sound as long as necessary to arrive at exactly the form he had in mind. The composer/technician could then assemble or edit scores of minuscule pieces (some lasted no more than 1/80th second!) so as to build new, exotic sound complexes. It did not need to resemble the traditional acoustic sounds produced by classical instruments. The electronics and editing technology provided composers with a whole repertory of new sound possibilities, a new musical dimension just waiting to be explored: the sound composition.

The process of making electronic tape music was very labour-intensive. In the 1950s pioneering sound engineers would spend hours and hours on a few seconds of music, which is hardly surprising given that they used measuring equipment which was usually designed for an entirely different purpose. The first generation of studios was not exactly what one might call user-friendly but they did produce magnificent works of art. Take, for example, Stockhausen's now famous 'Gesang der Jünglinge' composed in 1956, which became one of the favourite works of John Lennon, Paul McCartney and Björk. In fact under the influence of these avant-gardists The Beatles came up with a recorded composition entitled 'Revolution #9', which appeared on their 1968 'The White Album'. But in other songs, too, like 'Strawberry Fields Forever' (1967), The Beatles, and above all Lennon, showed a healthy interest in sound experiments.       

The difficulties involved in making electronic tape music led to musicians and engineers working together in the 1950s and 1960s. The Institute for Psychoacoustics and Electronic Music (IPEM) in Ghent, which was jointly established by the NIR and the University of Ghent, is a case in point. The IPEM was led artistically by radio producers and composers Louis De Meester and Lucien Goethals, while lecturers from the university's Low-Voltage Laboratory provided the technical input. The sequencer bench, now in the mim, attests to the intimate cooperation between the two specialisms in the 1960s and 70s. Such equipment was intended to simplify the process of making complex sounds. The sequencer technology led to the simplification of programming - not unlike computer programmes - what had been exclusively manually-operated equipment. The sequencer sends out a sequence of control voltage signals which can change the settings of devices like oscillators and filters. From then on Goethals and De Meester no longer had to generate, transform and cut each particle of sound separately, for the equipment immediately produced a sequence or succession of resonate parts.

Early electronic studios like the IPEM greatly influenced the development of audio technology. These days sequencers are widely used in the world of popular music. Such institutes were often the first to experiment with computer applications in music, a field which is still undergoing exploration. And the music which was produced there may be some of the most advanced and radically new in the history of Western music.

Music and technology have always gone hand in hand, from the first whistles made from animal bones through Cavaillé-Coll's high-tech organs and the electronic studios to today's artificially intelligent music computers and robots. IPEM's equipment is a testament to musical creativity, artistic curiosity and the drive to develop, which went beyond what musicians were offered in their own time. This experimental technology helped determine the face of contemporary music.

The historical IPEM studio equipment is a pemanent loan from IPEM, Gent, to the mim.

IPEM studio equipment in 1960 (post card)