The technology used here corresponds to a virtual artificial head . The sound from each of the five sound channels is digitally distorted in such a way that the brain perceives it as coming from a certain direction, e.g. B. from a loudspeaker behind the listening position. In contrast to previous solutions, Dolby Headphone also includes the acoustic structure of the imaginary space by simulating reverberation and adjusting the time delay of the individual, virtual sound sources.
Although humans can locate noises from all three dimensions with two ears, sound technology now uses up to seven loudspeakers to represent a spatial sound. With Dolby Headphone it is possible to reduce the technology back to two “loudspeakers” within the headphones, with the maximum hearing impression of a 7.1 system being achieved.
Dolby Headphone translates a multi-channel sound source into an artificial head stereo signal. This can be achieved analogously by playing the sound on a 7.1 Dolby digital system and recording it again as a normal stereo track with an artificial head stereo microphone. The artificial head stereo track can then be listened to with any normal stereo headphones. The detour loudspeaker → microphone is emulated in software with Dolby Headphone. Psychoacoustics have now developed very good and closely guarded procedures that reproduce the Dolby Digital sound in headphones very well.
The same algorithms are used for virtual Dolby in most high quality televisions. A 5.1 Dolby digital sound is reproduced there with only 2 speakers. Since the speakers are not on the ear, the quality is not (yet) as good as with Dolby Headphones. To improve this, the reflections of a so-called “normal living room” are emulated for certain frequency ranges and included in the artificial head signal using software. The manufacturers of virtual Dolby televisions already speak of a 1: 1 sound reproduction of the 5.1 audio signal, which, however, may only be true for some top-of-the-range devices and for use in a "normal living room".
Dolby headphone technology is now not only available as an add-on device, it is integrated into A / V receivers or, relatively inexpensive, already completely built into so-called "Dolby headphones", which in the headset version are via the universal serial bus connected to a PC , notebook or netbook . The included software enables a variety of real-time remixes. If used too often, however, the sense of the original threatens to be lost, as the newly acquired acoustic impressions are difficult to discuss. However, there is also the option of purchasing Dolby 5.1 headphones with a normal cinch or jack plug. Without the supplied sound software for computers, however, the possibilities for sound transformation shrink to a minimum. Some of the cell phones in the Lumia series from Nokia also support Dolby Headphones.
A similar Dolby technology - Dolby Virtual Speaker - claims to be able to do the same with external speakers.
- Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.): Manual of the recording studio technology . 2 volumes. 8th, revised and expanded edition. Walter de Gruyter, Berlin / Boston 2014, ISBN 978-3-11-028978-7 .
- Thomas Görne: Sound engineering. Fachbuchverlag Leipzig in Carl Hanser Verlag, Munich et al. 2006, ISBN 3-446-40198-9 .