Our movies and offices are engineered to sound natural based on what rang false in the theatres of 18th-century Paris

A low-level hum of talking and typing punctuated by the occasional warble of a ringing phone: the ambient murmur of a large open-plan office is, to a surprising degree, an intentionally orchestrated one. Not only do office designers use carpeting and absorptive ceiling tiles to reduce reverberation; in some cases they even distribute loud employees and machines around the office deliberately to mask one another and create a blanket of low-level noise in which individual sounds don’t stand out. The goal is to create an acoustic mise en scène that seems natural for office work. As the British architect Francis Duffy puts it, with too little background babble, ‘the environment as a whole seems “dead”.’

Improving how things sound in buildings – making certain sounds audible and attenuating others – is the aim of a multibillion-dollar acoustics industry. Paradoxically, one of the guiding objectives of architectural acoustics over the past 250 years has been to make built spaces and the acts of communication that take place in them seem as natural and unmediated as possible. Hence, the Dutch engineer Roelof Vermeulen once remarked wistfully that ‘the better [an acoustician] does his work, the more natural the result will appear and the less thanks he can expect.’

If you’re a middle-class Westerner, chances are you have internalised expectations for how a room should ‘naturally’ sound. You probably expect its ambient acoustic properties to match its function and visual character. The length and intensity of reverberation, the tendency for sound to resonate at particular frequencies, the background noise characteristic to that particular space – all these factors give clues about the size, form and contents of the environment. Moreover, when you hear a sound, you likely take for granted that it reaches your ears with minimal distortion, and that people located in different parts of the room perceive it in more or less the same way. Finally, you probably assume that your eyes and your ears will give consistent accounts of what the room is like and where sounds are coming from.

In most small buildings, no special effort is required to achieve these results. But large rooms of all kinds – restaurants, airports, hospitals, offices – are painstakingly engineered to meet our acoustic expectations. Making buildings sound natural is not the same as improving the clarity of sound, a goal recognised in the ancient world and discussed in the earliest surviving architectural treatise, by the Roman architect Marcus Vitruvius Pollio. This objective persists today, of course, but the goal of clarity is sometimes in tension with that of naturalness – a distinctly modern ideal arising from an elusive promise of fuller, freer communication and better mutual understanding.

A helpful analogy for the work of an acoustician is the creation of a movie soundtrack. Much of the sound we hear in a typical movie is either created or substantially altered in post-production. If the sound were simply recorded along with the picture and left at that, the microphone would pick up too much background noise and not enough dialogue. An engineer therefore adjusts the intensity of the audio at different frequencies, adds or filters out ambient sound, and introduces a subtle amount of reverb, so the sound matches the spatial environment shown onscreen. When we watch the resulting scene, our brains match up the visual and auditory tracks to suggest a complete illusory world.

The sonic conventions that govern most movies were worked out in early 20th-century Hollywood. Technicians argued over the best way to make a film sound believable – to achieve ‘artificial naturalness’, as audio engineer Wesley C Miller put it in 1929. For example, some initially felt that every time the camera cut between a wide-angle shot and a close-up of someone speaking, the loudness of the sound should change too. Eventually, though, most engineers agreed that if the audio kept shifting in this way to match the image, the soundtrack would draw too much attention to itself and would come across as unnatural. Today, cinematic sound tends to maintain the same ‘perspective’ even when the camera’s viewpoint changes. Ironically, letting visual and audio tracks subtly diverge like this yields a more natural-seeming result.

Movie soundtracks became an object of historical study in the 1980s through the work of Rick Altman and other film scholars. Altman was one of the first to use the term ‘sound studies’, which has since blossomed into an interdisciplinary area of research. But many of the concerns it has raised about sonic media and space have much older roots in architectural theory. When Hollywood technicians debated how to make movies sound natural, they were unwittingly following a trail blazed by 18th-century architects, who spent decades working out the acoustic conventions of modern theatres.

Eighteenth-century Europe is often said to have elevated the epistemic status of vision above that of the other senses – hence the optical metaphor of ‘enlightenment’ – but it also made sound an object of empirical research, commerce and artistic exploration. The public’s preoccupation with new auditory experiences was especially evident in the music world. The flourishing of the sonata (Italian for ‘sounded’) typified the new popularity of music without words. Alongside melody and harmony, audiences began focusing on timbre, which Jean-Jacques Rousseau – who was not only a philosopher but a composer, too – described as a sound’s ‘je ne sais quoi’.

What truly brought acoustic concerns to the fore, though, was the building of theatres, for both operas and spoken plays. Theatre stood at the centre of prerevolutionary French culture, a key site for philosophical reflection, political struggle and the construction of the self. It was also big business. The end of the Seven Years’ War in 1763 triggered a boom in domestic projects such as the construction of performance halls, which might contain 2,000 seats or more. Urban stages were graced by celebrity actors such as David Garrick and Clair Josèphe Hippolyte Leris (known as La Clairon), whose larger-than-life reputations were built up through published theatre criticism.

Audience members now saw themselves as consumers in an increasingly diversified entertainment market and demanded to hear every nuance of the plays they attended. […]

Read more: On the art and science of making buildings sound natural | Aeon Essays