Since the beginning of recorded and mediated sound, attempts have been made to replicate hearing sound in 3D space. In the early 21st century, technologies based on sonic objects are enabling new kinds of aural experiences for audiences.
When sound recording first started, and recorded sound was first replayed in theatres, the audio signal was in mono – that is, it didn’t include any directional information. While stereo sound was first experimented with in the 1880s (D.06), and there was some adoption in cinemas from the late 1930s, stereo was only adopted widely in cinema, radio, television and home music replay from the 1960s onwards. Stereo gives a spatialised sound – so the listener can place different sounds in different spatial locations between the two loudspeakers – but only for listeners in a particular position relative to the speakers. For listeners ‘off axis’, the illusion of a sonic space collapses, much as the visual perspective of the Italianate Renaissance and Baroque theatres failed for off-axis viewers (F.03).
In theatres, bespoke systems for particular productions were developed from the 1960s onwards (D.09), allowing sounds to be directed to one or more speakers located around the performance space, for example from behind the audience, or from off stage left. One early example of multichannel sound for a live audience was the Philips Pavilion at the 1958 Brussels World's Fair (Q30637), designed by Iannis Xenakis (Q30638), which used 425 loudspeakers to move sound throughout the pavilion. In 1967, the rock group Pink Floyd experimented with quadrophonic sound, performing the first-ever surround sound concert at Games for May, at London’s Queen Elizabeth Hall. The custom sound system used four channels to move sound around the space, controlled by the purpose-built ‘Azimuth Co-ordinator’ with its dual joysticks.
By the 1980s, surround sound was becoming established in cinemas, and later in home cinema set-ups, as some consumers sought to replicate the cinema experience in their living rooms. Various systems have been developed, based on stereo, with extra speakers for sounds behind and to the side. In addition to these commercial systems, there have been many experiments in more immersive sound, which include height information as well as horizontal direction, using overhead speakers. All these methods have the same disadvantage, however: the sound must be recorded, edited and processed specifically for the system that will be used to replay it. For theatre and live event use, where each venue, and often each show, is different, and some sound may be live as well as pre-recorded, these surround-sound technologies have been too inflexible.
Theatre has occasionally experimented with other kinds of sonic experience. In The Encounter (2015), by theatre company Complicité, directed and performed by Simon McBurney, the audience all wore headphones. The sound design made extensive use of a ‘binaural head’ – a life-size model of a human head with microphones in the ears. By feeding the binaural signal into the audience member’s headphones, they were, in sonic terms, placed in the position of the head on stage. At the start of the performance, McBurney introduced the audience to the head and demonstrated the binaural effect, walking around it as he talked, whispering and blowing in the head’s ear, and so on. The effect combed great intimacy in the sound domain with a sense of distance in the visual domain, which was central to the experience of sharing the main character’s journey deep into the Amazon rain forest.
In general, however, headphones are unsuited to theatre or live performance use. What is needed is a way separate the audio content from any particular configuration of speakers, so it can be replayed in any environment. After some false starts, including the 1979 Ambisonics system, technologies are emerging that can provide this separation, and may have a substantial impact on spatial audio. Dolby’s Atmos system is based on ‘sonic objects’ – a sound source that is associated with a particular position in space relative to the listener. The same audio content can be deployed in different contexts, with the decoder maximising the spatial effect for the listener with the speaker system being used, from a cinema sound set-up to a pair of earphones. Soundscape, developed by d&b audiotechnik, is a system using sonic objects that can also simulate different acoustic environments. Soundscape is targeted specifically at live performance; it can place up to 64 sonic objects in three-dimensional space relative to the listener, aiming to align the sound’s position with it’s visual position. Soundscape has been used on the 2022 production MJ the Musical, a jukebox musical featuring the music of Michael Jackson. The system both ensures the sound heard through the speakers is spatially aligned with the performers on stage, and emulates various acoustic spaces for different scenes, as Jackson performs in different venues from an intimate club to an enormous stadium.
The story of spatialised sound began in the 1880s. Now, in the early 21st century, new technologies and new methods are giving theatre-makers ever-greater scope to position sound in space, extending the kinds of sonic experience they can offer audiences.