The Electrostatic Free Wave Sound Monitor Project

The next approach to the ideal source for sound reproduction was using electrostatic forces. Electrostatic speakers with their big-sized low-mass membranes are well known, but they all share the same basic problems: as dipole-radiators they send the same amount of acustical energy backwards out of phase (this is not much of a problem if you have a large, acoustically well-damped listening room). They are excellent for low sound pressure reproduction but not for high listenig levels. They radiate with strong directivity. They have notoriously weak low frequency response, first because of acoustic short-circuiting and second due to the limitation of electrostatic force in a conventional atmospheric environment.

Most of these problems can be overcome when using an acoustical transducer as a headphone in the acoustical near-field domain instead of listening in the far-field of a speaker. So I developed my own system about the same time as Jürg Jecklin (a well known Swiss sound engineer) developed his model.

My approach was different. I wanted a light, unobstrusive, adjustable and storable system not only open around the ear, but acoustically fully transparent to the outside. You could test the benefit of this easily in a noisy environment: put the palms of your hands parallel in front of your ears without touching them, at the same distance you would wear an electrostatic headphone. Immediately you realize that your acoustical perception of your environment changes dramatically. Now you wear odinary electrostatic headphones (without yet listening to music) and you put your palms again before the headphones. Now, with normal electrostatic headphones, your perception will not change, because the headphones have already changed the acoustical situation if they are not designed sufficiently transparent. They have added their own footprint yet before listening to music.

With my headset on, you still hear the difference when you put your palms in front of it. That's why I named my transducers "Electrostatic Free Wave Sound Monitors". Paradoxically, the best headphone is the one who "is not there". The sound is absolutely transparent, the bass response is excellent, except for those extremely low frequencies where you should rather feel than hear. This monitor, combined with a strong subwoofer system (to physically "shake" your body at the low frequencies of a kettle-drum) is - in my experience - the best way to reproduce good binaural sound recordings.

For multichannel listening there are other solutions.

I held a patent for my approach and some construction details. In my laboratory - well equipped with electronics, a turning lathe, milling machines and the like - I produced moulds to start a small series of several prototypes, some of them are still working.

Due to other priorities as an assistant at ETH and later starting my industrial career, I never focused on marketing the system.

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