The following was written by Florian Koenig:
"...the technology behind the S-Logic [is] based on the following principles:
* For circum-aural headphones, the speaker needs to be placed at an angle of 30 to 40 degree de-centric (lower/frontally based on the hear channel). The bufferboard should be acoustically hard (reflect for lower frequencies) and damp (for higher frequencies). The upper area of the speaker is to close or damp at about 30 percent of the diaphragm-reflecting zone to optimize the de-centric placement optionally.
* For supra-aural headphones, the speaker needs to be positioned near the centric or slightly lower on the ear channel. The bufferboard should be acoustically hard for the total frequency range. The upper area of the speaker is to close at about 50 percent of the diaphragm-reflecting zone, creating a de-centric placed sound source in front of the ear channel.
* The ear pad needs to be chosen to ensure tone with maximum emphasis free of colorations. For open headphones, a velvet or cloth surface is preferred. For closed headphones, the ear pad should be genuine or synthetic leather.
The speaker should be gold or Titanium-mylar diaphragm and developed for an extremely hard burst response (THD spectral delay time at frequencies greater than 1 kHz about 0,9 ms). The drivers allow for very low frequency tone signals (<40 Hz) without phase-masking effects and without the perception of the real tone signal (not the THD) first (transmission frequency could be offered up to 35 kHz). These tone-neutral aspects are important in the reproduction of the clearest and cleanest natural spatial sound, effects and the lateral wall reflections, phases as a function of high dynamic audio signals (>100 dB).
The development of new headphones is a permanently growing process led, in part, by new technology and market desires, but the metamorphosis of steps from mono to stereo to S-Logic (natural surround sound) has had to proceed sequentially to fully understand the effects of each on future technology. A documentation of the results of the past makes it possible for bi-directional observations of the acoustics effects.
In studying the past, it is clear that S-Logic is the only way to influence stereo or channel tone signals to produce a 3-dimensional auditory event without any digital, binaural processing, apart from the mean human HRTF of a dummy-head (hint: recordings with more ambient feeling, but the old well-known above in the head localization). The human outer ear (pinna) fluctuates more than 15dB at frequencies less than 1kHz (standard deviation 6 KHz =7dB!). These individual hearing realities cannot be served with only one headphone. HRTF is the only logical consequence. And, since the tone recordings offer no 3-directional information regarding common pan-pot stereophonic recording techniques, the only solution is S-logic.
Unique to the Ultrasone is its patented S-Logic technology. S-Logic utilizes decentralized transducer position to reflect sound off the listener's pinna, or outer ear, creating a natural 3-dimensional sensation without the use of processing. Whereas standard headphones create the impression of stereo image within the listeners' head, S-Logic produces a stereophonic surround sound field that is perceived to be broad, detached, and located in front of the listener. Ultrasone is the only headphone manufacturer to directly address the physiology of the ear rather than use electronics to generate a stereophonic sound field.
Moreover, since the headphone transducers are not aimed directly at the auditory canal, listeners perceive the same volume with up to 40 percent lower sound pressure levels. This may significantly reduce risk of hearing damage while ensuring hours of fatigue-free listening - an absolute must if you spend half of your life in headphones.
Finally, most headphone drivers today convert an electric signal into an acoustical signal, producing low-frequency magnetic fields. Medical research shows that these emissions can be hazardous to our health. In response, we developed special MU metal shields to reduce the radiation up to 98 percent compared to current headphones. The patented PROline (ultra low-emission) technology has stood the test of international review and is recommended by technical surveillance organizations."
Recommended and scientific papers around S-Logic and PROline are available from the Audio Engineering Society (ww.aes.org) published in 1995/1995/1997/2001/2004.
Florian M. Koenig is the founder and chief technical officer of Ultrasone.
