Under The Influence of Sound

An Introduction To Psychoacoustics

David Werbrouck on Unsplash.com

There is an old aphorism that says god is in the details. If you are one of those audiophiles who chooses a car based on the audio system inside, you know what I am talking about. Perhaps, you are the kind whose world is a whirlwind of choices to appease your earbuds or you are a music gourmand who believes that the purest form of a love affair is the one between music and your ears. This article talks about the science behind that love affair called psychoacoustics.

In 1860, Gustav Fechner in his book ‘Elements Of Psychophysics’ coined the term ‘psychophysical’. The term Psychoacoustics means the study of the psychophysical affects of acoustics. The word acoustics means relating to sound or hearing. A sound is nothing but a propagation of air waves by whatever made the sound. The human ear is an incredibly complex and beautiful analog to digital sound converter.

Around 350 BC, Aristotle was the first one to suggest sound was created by air waves. Many prominent scientists and philosophers such as Galileo, Kepler and Descartes studied different parts of psychoacoustics in the past. The seminal works of Hermann von Helmholtz and Gustav Fechner turned Psychoacoustics into a compilation of observations and a more scientific approach to sound and its effects on us. Their work focused attention on pitch and sound source localization.

In recent times, the study of sound and music and their impact on human cognition has been studied by computer scientists and audio system designers. Psychoacoustics is the scientific study of sound perception and audiology — how humans perceive various sounds. There are people in this world that dedicate their lives to studying how sound affects our mind and body ie our psychology and physiology.

Psychoacoustics lie at the intersection of physics, engineering, psychology, biology, physiology and computer science. It is a deep rooted science because we just don’t hear a sound. Once the sound enters our ears, it is converted into neural stimuli. Some differences in sounds are imperceptible when the ear converts the sound into neural stimuli. Therefore, MP4 (Motion Pictures Engineering Group-4) decompresses some sounds to reduce file size. Once our hearing has been converted into neural stimuli, our brain then instructs our body to take action such as dancing.

The Basics Of Sound

We measure the loudness of sound in decibels (dB) and the sensation of frequency in hertz (Hz). A normal human can hear frequencies ranging from 20 Hz to 20000 Hz (20 mHz). An example of a low pitched sound is a bass drum and a high pitched sound is a whistle. Thus, in music — frequency has three settings ie bass, mid and treble ie low, medium and high pitch. As per Wikipedia, the term “treble” derives from the Latin triplum, used in 13th century motets to indicate the third and highest range. It denotes the pitches of Sopranos and piccolos etc.

There are three measures of the loudness of sound ie absolute threshold of hearing (ATH), discomfort level and normal levels. ATH is the lowest level of air pressure needed for us to hear in silence. Discomfort is the threshold where sound creates discomfort.

Although theorists such as Benjamin Boretz consider Psychoacoustics to be relevant in a musical context, it has wider implications.

As far as music is concerned, the million dollar question always has been : why do we like some kinds of music ie how can we explain our musical preferences. There has been no robust scientific explanation of our taste in music. Our environment, personality and even the people we hang out with can make a difference. Let me give you an example.

In the first year of my college, I firmly believed heavy metal to be a noise producing factory. A bunch of machines grinding while an undecipherable voice sang words that would not reach my ears. One of my friends introduced me to the unplugged version of Metallica’s Nothing Else Matters. Then, I slowly progressed to death metal. The point I am making is that sometimes it takes a good friend to open your earbuds to a different kind of music. Maybe you like it, maybe not. I always have my Shazam app handy in retail stores, during Uber rides and in hotels. I am always curious to know what sounds the world likes. Music has an uncanny ability to unite us as a species.

Two of the most important applications of Psychoacoustics is its application in the creation of synthetic music (DJing) or in the realm of computer science. The resting heart rate of an average human is 60–100 bpm. Tempo in music is the rate or speed at which sound can be passed on. The number of times a pattern of music repeats itself is called ‘a beat’ . Beats are measured in beats per minute (bpm). Music tempos have a variety of effects on the human heart, blood pressure etc. We can increase the tempo or reduce it to have our bodies respond. For instance, electronic music gets us in the groove by playing 120 bpm or more. The metronome, invented by Johann Nepomuk Maelzel, made the measurement of tempo very popular.

There are many things beyond tempo that determines how music affects all of our lives. It is hard to capture magic in a few sentences. Therefore, the idea was to give you a flavor.

Beyond The Realm Of Our Senses

We hear what we want to hear. Similarly, our sensory experiences guide our perception of the physical world. Not everyone reacts the same way to the darkness or to colors or smells and fragrances. Therefore, experience designers spend millions of dollars on creating fragrances, sounds and flavors that delight us. There are deep scientific principles at play while creating these micro universes that we can enjoy. Luxury automobile manufacturers have their own tie ups with audio manufacturers eg Jaguar Land Rover has a partnership with Meridian audio while brands like Audi have a tie up with Bang & Olufsen.

Man has created too many objects of desire and instruments to give mankind pleasures. If we are not careful, these creations also restrict our understanding of the world to our sensory perception. There is whole world out there that lies beyond the realm of the physical sensory experience.

There is also a world where people cannot appreciate the power of our senses because they don’t have food, clothing or shelter on their body to even think about higher order sensory experiences. The World Bank estimated that approximately 702 million people live in poverty across the world in 2015. This is down significantly from 1.1 billion in 1990.

I started writing this article for my readers to learn and enjoy the science behind sound and music. However, I also wanted to urge my readers to think about providing basic sensory experiences to others if they want to. In doing so, live for others. Our experiences may define our life but when all else is done, each one of us is defined by our deeds.

Writer @ The Intersection of Finance, Tech & Humanity. Stories of a Global Language: “Money”. Contributor @ Startup Grind, HackerNoon, HBR. Twitter@akothari_mba

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