Evolving views on HOA: from technological to pragmatic concerns (invited)

From first fundamental studies in the mid 90's to today, Higher Order Ambisonics (HOA) keeps being investigated through various view angles, highlighting increasingly nice and numerous features. From the beginning, the relevance and flexibility of acoustic field reconstruction and representation format introduced HOA as a powerful approach benefiting to a large scope of contexts. Nevertheless, if one may dream of it as the format and/or generating approach for future immersive contents, making this dream a reality requires further steps: integration of content generating tools; use, adaptation and assessment by content creators / sound engineers; consumer equipment/acceptability; coding scheme development, format standardisation and compatibility. In this talk/paper, the author will outline contributions, position and expectations of Orange Labs regarding these aspects. As a turning point has been the design of HOA microphones, opening an exciting experimental field in terms of real 3D sound field recording, the author will also share experience and thoughts from experiments involving (or not): video capture, other sound recording approaches, live or post-produced diffusion, etc. In particular, the quite pragmatic, but difficult exercise of targeting standard 5.0 format and ITU setup (with short-term concerns close to the mass market) raises itself essential issues. Indeed, the potential spatial instability and incompleteness due to this quite unbalanced setup may force to: reconsider decoding strategies, mistrust audio monitoring over other setups, go against the spatial fidelity principle and rather use spatial separation capabilities to construct a twisted projection of the recorded sound space (especially under microphone positioning constraints).