A Brief On Acoustical Engineering

Let us take you back to 600 BC when an ancient Greek philosopher, Pythagoras, was looking for an answer to the question: Why are some combinations of musical sounds felt to be more impressive than other ones? And what he found was numerical ratios that represent a harmonic overtone series on different strings.

He observed that when the lengths of vibrating strings are expressible as ratios of integers, the tones will be harmonious. And the smaller the integers, the more balanced the sound. That’s when the concept of ‘acoustic’ first came to be.

Acoustical engineering is a particular branch of engineering that deals with sound and vibration. And speaking of ‘dealing with sound and vibration,’ we are talking about every single parameter responsible for creating vibration and, as a whole, sound.

Acoustic is, in general, mechanical waves in gases, liquids, and solids, which include topics like vibration, sound, infrasound, and ultrasound. An acoustic engineer works in the field of technology related to acoustics. In almost all aspects of modern society, the application of acoustics is present in the most obvious- the audio and noise control industries.

Speaking of noise control, one of the primary goals of acoustical engineering is eliminating or minimising unwanted noise. It is also referred to as noise control or noise cancellation. Unwanted noise can have significant impacts on animals as well as human health and well-being. Such unwanted noise negatively impacts students and patients while also causing hearing loss.

‘Hearing’ is one of the most crucial means of survival, and ‘speech’ is one of the most idiosyncratic characteristics of human development and culture. Consequently, the science of acoustics spreads across many facets of human society, like- music, architecture, medicine, warfare, industrial production, and more.

By the same token, animal species, like songbirds and frogs, use sound and hearing before mating or just marking their possessions. Art, science, craft, and technology have provoked one another to advance the whole, as in many other fields of knowledge. These all are fine until you get some noise from them. And if you would like to cancel the noise, you have to follow some rules.

Well, noise cancellation principles are implemented into technology and design in various ways. It includes control by redesigning the sound sources, noise barriers, sound absorbers, suppressors, and buffer zones, and, most definitely, the use of hearing protection. It’s not quite impeccable in terms of surround sound, for example- a Bluetooth speaker, but it works on today’s earbuds and over-ear headphones which are without any kind of audio jack.

However, acoustic engineering is not only about noise control; it’s a lot more than that. It covers positive uses of sound, ranging from the use of ultrasound in medicine to the programming of digital sound synthesisers. From designing a concert hall to significantly enhance the sound of the orchestra to specifying a railway station’s sound system for announcements- acoustical engineering covers it all.

Back in 20 BC, a Roman architect and engineer named Vitruvius wrote a treatise or thesis on the acoustic properties of theatres, including a discussion of interference, echoes, and reverberation. In Book V of his ‘De architectura,’ also known as ‘The Ten Books of Architecture,’ Vitruvius describes the sound as a wave comparable to a water wave extended to 3-dimensions, which, when interrupted by obstructions, would flow back and break up the next waves.

He described that the ascending seats in ancient theatres were designed to prevent this deterioration of sound and also recommended placing bronze vessels of appropriate sizes in theatres to resonate with the 4th, 5th, and so on, up to double octave, to resonate with the more desirable, harmonious notes. Such works on sound architecture were the beginning of acoustical engineering.

Now let’s take a tour of some branches of acoustical engineering.

Architectural Acoustics

Building acoustics or architectural acoustics is the science and engineering of achieving a decent sound within a building. Architectural acoustics is mostly about achieving good speech intelligibility in a restaurant, a big theatre, or a railway station, upscaling the quality of music in a recording studio or concert hall, or just suppressing noise to make our offices and homes more productive and pleasant places to work and live.

Bioacoustics

Bioacoustics generally concerns the scientific study of sound creation and hearing in different animals. It attempts to comprehend acoustic communication and associated animal behaviour and the evolution of the species, how sound is produced by different animals, the auditory mechanisms and neurophysiology of them, the use of sound to monitor animal populations, and of course, the effect of artificial noise on animals.

Electroacoustics

Electroacoustics deals with the design of all types of headphones, speakers, microphones, and other sound systems. There’s been an overwhelming increase in the use of portable electronic devices which can recreate sound and rely on electroacoustic engineering, for example, mobile phones, portable media players, and tablet computers.

Musical Acoustics

Musical acoustics is concerned with researching and describing the physics of music and its perception. It seeks answers to questions such as how sounds are employed as music works. It also includes the function and design of musical instruments, such as electronic synthesisers, the clinical use of music in therapy, human singing, computer analysis of music and composition, and also the perception of music.

Speech

Speech is a prime area of study for acoustic engineering, including the production, processing, and perception of speech. It may include physics, physiology, audio signal processing, psychology, and, obviously, linguistics. Speech synthesis and speech recognition are two essential aspects of the machine processing of speech. It ensures proper, efficient, and high-quality speech transmission and is also another important study in acoustic engineering.

Final Words

Acoustical Engineering is a well-explored field, focusing on a broad range of subject matters. Historically, it has been focusing on ensuring our health and well-being while expanding the scope of experiencing sound differently. Whereas it was impossible to present all about it within one article, we attempted to capture its essence and contribution to our modern lives. We hope to celebrate more groundbreaking development in this field in the future.