Spatial Audio definition (vs. spatial sound and 3D sound)


    As someone who has dedicated his career to understanding and developing audio experiences, I recently had the opportunity to dive deep into the topic of spatial audio with Thomas Riedel. Especially in the context of the new Apple Vision Pro, his podcast is no longer called Metaverse Podcast, but “Spatial Realities”.

    More up-to-date than ever with Apple’s VR glasses

    In our discussion, one example, we explored the fascination with all things audio and the increasing importance and sound field of 3D audio, which is no longer limited to Apple devices, but is also being adopted by other manufacturers and in various media such as films and the music industry.

    3D audio is slowly becoming mainstream. […] There was quite a lot of coverage, even in the Süddeutsche newspaper, where I was somehow quoted once

    Podcast with an immersive experience that is not dolby atmos

    Listen to the whole episode here. The article is based on a 10-minute discussion about the difference between immersive audio, spatial audio work and sound, traditional surround sound here, and sound waves etc. I hope there is now a better 3D audio definition Spatial Realities Episode 43.

    The evolution of 3D audio from surround sound

    Moving on, it is crucial to emphasise the significant differences that 3D audio offers compared to traditional audio formats such as stereo and surround sound.

    “If you say you can move and hear the surround sound on one plane, front and back, the left ear and the right ear, then I would say Dolby Surround is two-dimensional. […] And only if I now start to be able to give height information to the object, then I would be in 3D in this area.”

    This explanation focuses on how 3D audio creates an immersive environment and interactive listening experience through the introduction of height information and the consideration of head movements, which not only surrounds around the listener with two ears but immerses them directly in the soundscape.

    The 3D Audio Matrix clarifies

    The definition of 3D audio depends heavily on the context in which it is used. It’s a question that can be answered by my ‘3D Audio Matrix’ – a concept I developed to visualise the different aspects and applications of 3D audio. More about this on my blog and in my training course.

    In the world of three-dimensional sound, there is often a confusion of terms, which I address in my interview with Thomas Riedel.

    “Many colleagues use Dolby Atmos and think they automatically create immersive audio. But many immersive media cannot be reproduced in the AC-4 format.”

    It is crucial to understand the differences between spatial audio, 3D audio and immersive audio, as they each emphasize unique aspects of sound quality in the listening experience. This clarity is necessary for users to fully enjoy hearing the advanced audio experiences that these technologies enable. When in doubt, you can rely on your ear – but here are a few definitions.

    What is an immersive audio definition?

    Immersive audio is an experience that allows you to immerse yourself in the sound itself, far beyond the limits of technology.

    “Immersive audio can also be stereo”

    is a realisation that emphasises that this type of audio experience is less about the number of channels or the complexity of the setup, and more about the feeling of immersion.

    A good song that gets you dancing in a club can be heard as just as an immersive experience as a complex multi-channel system. Immersive audio creates an atmospheric, immersive playback room-filling sound world that captivates the listener regardless of the technical realisation.

    That’s why I find it critical when “immersive audio” is used as a synonym for “better” in an attempt to upgrade stereo and sell it at a higher price. You have to differentiate between immersive audio systems, or streaming platforms, i.e. technologies, and immersive content, services, i.e. experiences.

    3D Audio: The spatial dimension of sound

    The true depth of 3D audio is revealed in the ability to move the sound in all directions. In contrast to two-dimensional sounds, where the sound can only be moved on one horizontal plane, 3D audio opens up a world in which sound objects float vertically and envelop the listener.

    “Only when I start to give height information to the object do we move into the realm of the three-dimensional. But even this kind of threedimensional sound is not enough.”

    This dimensionality makes it possible to navigate in a sound sphere, to move towards or away from sounds, which is particularly important in the world of virtual reality and interactive games. This is where the concept of degrees of freedom quickly comes into play.

    If I can rotate my head, this process is called dynamic head tracking and has three degrees of freedom of rotation. Apple’s headphones already make this possible. Sounds crazy, right channel but this technology gives me five different playback options with my ears on these 3D Audio headphones. The blog article reveals more.

    With six degrees of freedom, you’re in the world of gaming, XR, VR, AR and spatial computing. The movement in space works without sound processes such as Dolby Atmos but in game engines. Apple’s VR glasses, with the Apple Vision Pro Audio Features also enable translation to audio objects.

    Spatial Audio: Apple’s immersive audio systems

    Apple has really understood and developed spatial audio. It has teamed up with Dolby Atmos, but this also causes a lot of confusion. Spatial sound is much more than Dolby Surround, which is ultimately a format that is only good for film and music.

    They have presented a lot of features of the glasses, but it feels like all their computers have additional speakers with spatial audio built in. But when is three-dimensional really three-dimensional?”

    I ask, pointing out that the use of 3D audio in a 360-degree video is different from that in music production or cinema.

    On the Apple homepage, the term ‘Spatial Audio’ is used, while the German translation is ‘3D Audio’. This reflects not only a linguistic adjustment, but also Apple’s efforts to make this advanced audio experience accessible to an international audience.

    “In German it’s ‘3D Audio’, and that suits us Germans who love numbers, data, facts,”

    I suppose to emphasise the precision and clarity that the term ‘3D Audio’ brings to the German language. This terminological clarity helps to convey Apple’s revolutionary technology and emphasise its importance for an immersive listening experience.

    I find “spatial audio” difficult in German and the sound effect produced is more reminiscent of delay and reverbs. Something from music production using classic audio formats.

    Apple Spatial Audio

    Apple combines object-based audio elements with spatial sound and ambient effects as well as independent stereo components to create a comprehensive spatial audio experience. The result is a listening experience that remains constant regardless of the viewing direction, which is particularly important for narrative voices or background music.

    This approach makes it clear that spatial audio is not just one component of spatial sound, but an interplay of different elements perceive sound that together create different sounds and a truly immersive audio experience.

    Read more about Apple’s spatial audio approach in the Realitykit here.

    Here is the short summary:

    • Object-based audio elements: Placement of sound objects in three-dimensional space so that listeners can perceive their position relative to the sound sources.
    • Spatial sound and ambient effects: Addition of reverb and wall reflections to create a more realistic sound environment.
    • Stereo without 3D audio: The ability to integrate stereo sound regardless of viewing direction, which is especially important for narrative voices or background music.

    Apple Spatial Audio is not a real term. For me, it is simply an umbrella term for headphones, computers, etc., as. Software and hardware from Apple that does something with 3D audio.

    Future and challenges of 3D audio

    The future of 3D audio is undoubtedly promising, but it is not without its challenges. In the discussion with Thomas, it becomes clear that despite the impressive technological advances and growing interest in 3D audio, many people and media still struggle to navigate between the different audio formats and experiences available.

    “Still, it’s a good sign that it’s getting more and more coverage.”

    The industry is faced with the task of designing these advanced audio experiences so that they are intuitive and accessible without a listener having to wonder which technology is being used. It’s about creating seamless transitions between formats and ensuring that content is always of the best possible quality, regardless of whether it is presented in stereo, surround or 3D.

    The onus is on both creators and consumers to develop a deeper understanding and appreciation of the subtleties of spatial audio. Enough theoretical definitions for today.

    Looking for an expert who can also go into practice, whether for headphones or speakers? Then write to me!

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