Enveloping3D - (Headphone-) Upmix
A. Problems with conventional headphone listening
Listening to headphones/earphones (to stereo recordings) is practical and in many situations there is no alternative - but listening pleasure has always been clearly limited in terms of sound quality:
a. The so-called "In Head Localization" (IKL) causes the (virtual) sound sources not to be perceived from outside of the head of the listener (normally one would have to perceive them from the front). This leads to a low physicality and narrowness of the sound sources, you can't really grasp them aurally and they have only a limited emotional impact on the listener.
b. Especially with older recordings, the (virtual) sound sources focus on 3 main directions of incidence: from the front, from the left and from the right. From the areas in between, i.e. half left and half right, the listener perceives significantly less, which not least leads to an incorrect reproduction of the level balance: the sound sources, which should actually be half left and half right, are perceived a bit quieter than they are actually meant to be.
With many (by far not all) newer recordings, the conditions of headphone playback are better taken into account in relation to this problem, and the described "holes" are then significantly less perceptible.
c. The spatiality contained in the recordings does not unfold "spatially" - instead it seems to the listener to come out of a narrow band between left and right and thus has something not quite tangible. The reverberation seems to collapse from the outside in - it would be desirable that it opens from the inside to the outside. An enveloping of the listener by the indirect sound like in good sounding concert halls cannot take place under these circumstances.
In this respect, loudspeaker reproduction (in conventional home audio way) incorporates the spatiality of the listening room into the listening experience - this leads to a dilution of the character of the overall spatiality (actually the recordings should not sound like being made in living rooms), but this is a better compromise in terms of sound aesthetics than the current headphones listening.
d. The bass reproduction of headphones is questionable even in models with strong bass; at least the fundamental tones of very deep sound components are underexposed in the listener's perception, so that deep tones lack "physical" assertiveness.
With all these problems, the cause is not to be found in the headphones themselves, on the contrary. Stereo was developed at that time for loudspeaker reproduction only, and it is remarkable enough how human perception can be "tricked" under these conditions.
B. The solution
In high-end circles, the "Holy Grail" of the audio industry is mentioned with regard to a solution to the problems listed above. In fact, the complex of problems is markedly multilayered, so that solutions only for individual problems sound immature and not coherent in themselves. The individual solutions themselves already are by no means trivial, but require the breaking away from traditional thought patterns and the introduction of unconventional ideas.
In a nutshell, with the Enveloping3D headphone upmix
a. the output stereo recording can be transformed into a HOA sound field,
b. the sound body (the sound sources) can be virtually moved forward from inside of the head of the listener, and
c. the spatiality of the recording can be 3-dimensionally expanded and the listener can be enveloped in a convincing way by this transformed spatiality.
A flat, small and sobering sound becomes a great 3D spatial listening experience that finally does justice to the music. The basses also sound fundamental and unobtrusive. In comparison, the conventional way of listening to headphones seems absolutely "historic". The Enveloping3D headphone upmix is poised to become the new standard for stereo listening.
C. The road to market maturity
It is still a fairly long way from the prototype of the upmix to market-ready products. Different quality levels are possible depending on the computing effort, so that high-end products can be expected as well as still very impressive sound solutions, e.g. for the smartphone.
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