How Noise-canceling Headphones Work
One person’s noise is another person’s music, but ambient noise is the enemy no matter what your musical preferences are.
It’s a good thing that there’s a piece of audio equipment built specifically to improve your listening experience by blocking out ambient noise without degrading the sound quality of your favorite songs.
The headphone is that piece of equipment, and in this post, we’ll take a look at how headphones, particularly noise-canceling headphones, operate.
When Amar Bose, the founder of Bose Corporation, boarded a journey to Europe in 1978, he put on a pair of airline-supplied headphones, only to discover that the roar of the jet engines prohibited him from listening to the audio content.
He started doing calculations right there on the plane to determine if it was possible to use the headphones themselves as a noise-reducing agent, and he finished them straight away.
Almost a decade later, Bose unveiled the world’s first noise-canceling headphones.
It is necessary to first comprehend sound waves in order to understand what headphones are doing.
You may learn more about how speakers work by visiting How Speakers Work, but we’ll also provide a basic overview of the process here.
Water waves, such as those seen in an ocean or a lake, are what most people envision when they think of waves.
A shallow water wave is an example of a transverse wave, which is defined as a wave that generates a disturbance in a medium that is perpendicular to the advancing wave’s path.
On the illustration below, you can see the relationship between the two variables.
In addition, the picture depicts how waves generate crests and troughs.
When there are two crests (or two troughs) in a waveform, the distance between them is known as the wavelength, and the height of a waveform (or the depth of a waveform) is known as the amplitude.
The number of crests or troughs that pass across a specific position in a second is referred to as frequency.
The characteristics of sound waves are very similar to those of water waves, but they are longitudinal waves that are produced by a mechanical vibration in a medium that results in a series of compressions and rarefactions in the medium. Sound waves are produced by compressions and rarefactions in a medium.
When you pluck a guitar string, for example, the string begins to vibrate and create sound.
The vibrating string initially pushes against the molecules of air (the medium), then pulls away from the molecules of air.
In the end, this produces an area where all of the air molecules are squeezed together as well as an area where all of the air molecules are scattered widely apart immediately next to it.
As these compressions and rarefactions propagate from one location to another, they combine to form a longitudinal wave, with the disturbance in the medium traveling in a direction parallel to the wave’s propagation direction.
Longitudinal waves share many of the same properties as transverse waves in terms of their fundamental qualities.
It is a crest that corresponds to compression, and it is a depression that relates to rarification.
The wavelength is the distance between two compressions, while the amplitude is the quantity of medium squeezed between the two compressions.
The number of compressions that pass through a specific position in a second is referred to as the frequency.
It is the amplitude (or loudness) of sound waves that determines their intensity (or loudness).
The pitch is determined by the frequency, with higher frequencies producing higher pitch notes and lower frequencies producing lower pitch notes as the frequency increases.
It is possible for the brain to interpret these qualities of sound; but, in order for this to occur, the sound waves must first be detected by a sensory organ.