When we think of immersive audio, we think of 3D sound – and it’s everywhere, from gaming to streaming music to live broadcasting, adding value to each presentation. According to audio and recording manager Gerardo Marrone, who has spent this summer producing a series of live immersive events at London’s Kings Place: “There has always been a sensory conflict between what you see and what you hear, but the main focus of the performance no longer has to be on the stage, and can provide an intimate connection between the art and the people. The audience becomes part of the performance, not just a witness to it.” Whatever the medium, spatial audio adds value and turns a presentation into an experience. But while more consumers are switching on to it, it’s nothing we haven’t heard before. BINAURAL AUDIO Binaural audio is a two-channel format which dates back to 1881 and provides an immersive environment by mimicking how our ears work. When we hear sound, we organically filter it depending on location. Binaural recordings take positional information from a pair of microphones and apply a filter, similar to how we do. We do this naturally using three localisation cues. The interaural level difference is how loud the sound is, so if it is louder in one ear we know the source is on the side nearest that ear, while the interaural timing difference is how long it takes to get from one ear to the other.
The third is head-related transfer function (HRTF), which provides information based on average ear and head shapes. It provides information for the height plane as well as position and distance. Binaural recordings are often created using dummy heads, complete with mics implanted in dummy ears. For programming, these effects can also be created artificially using delay and panning on an audio workstation or mixing console. The reason we’re banging on about it is because binaural mixes are a big reason why immersive audio is so popular. Binaural is a standard two- channel delivery, so consumers only need a pair of headphones to experience it. And as Qualcomm knows, this is the preferred delivery method to millions of phone users across the planet. THE BIG NAMES Developed in 2012, Dolby Atmos has done more to popularise immersive audio than anything else and is the most recognisable encoded immersive format around. It consists of essentially a 5.1 or 7.1 surround mix, with additional speakers in the height channel. Apple Music is another early adopter that has worked hard to bring spatial audio to market, with millions of people experiencing it through Apple Spatial Audio, which decodes Atmos content to a binaural format across thousands of songs on the streaming service. These implementations have helped consumers appreciate the benefits, and the content production industry is responding positively, with stereo albums
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