Standardizing the Immersive Audio Playback Chain

If you follow my posts, you’ll know that spatial audio measurement is a big research area for us right now. As immersive audio takes off, it’s important that designers of spatial audio systems have the tools they need to accurately measure spatial sound characteristics such as localization and envelopment. This will enable consistency in playback so that artists and mixers know that the effects that they are creating sound as they intended, no matter what the consumer’s playback equipment.

To complicate the issue, having designed the playback system, manufacturers also need to take into account the myriad ways in which their customer may configure their speakers to ensure consistent reproduction. This is no simple task when room acoustics also comes into it and few consumers have a perfect listening space.

While we are some way from having universal measurement techniques and standards, I witnessed an interesting insight into how Genelec is addressing the issue of customer configuration at the AES/ASA/BAS Boston chapter meeting at their facility in Natick earlier this week.

First we received a demonstration in their newly-configured immersive room where they demonstrated several soundtracks. This included correlated and uncorrelated pink noise at low frequencies to illustrate bass reproduction. They also played a couple of musical pieces including the musical score from a video game (which was surprisingly impressive) and a piece of Indian music. These were both very immersive, with sound coming from multiple directions. What I found interesting about this was that in the 9-seater listening room, there was really only one sweet spot or seat where you received the full impact of the immersive experience. The effect in the other seats was not uniform and depended on the seat’s position relative to the center spot. This will certainly present challenges to sound designers!

In a separate room, we saw how Genelec helps their customers ensure that their equipment is correctly configured. This was impressive too! Their bespoke software uses a microphone and network adaptor to make measurements in the room and upload them to a server. The speaker-room interactions are diagnosed, and their software returns a comprehensive report including frequency response, time response and time-frequency analysis including wavelet analysis. It also provides an electronic file that equalizes and time-aligns the speakers to compensate for the room characteristics and exact speaker placement. This ensures that Genelec’s customers are hearing the sound as they intended, regardless of their room configuration.

This is a great start, and it’s encouraging to see spatial audio playback system vendors following through to ensure the end user’s experience is as intended. However, this is only one part of the puzzle. There is still a need for the industry to agree on useful metrics that allow manufacturers to design and evaluate their systems to Dolby Atmos and other spatial audio specifications. This will allow the creative effects of spatial audio to transcend individual manufacturers and allow consumers hear exactly what the recording engineer intended, regardless of their chosen brand of playback equipment. If you make spatial audio playback equipment, what metrics do you think show the most potential for evaluating spatial sound effects? We’d love to hear from you.