April 26, 2024

Sound Science: Great Headphones Blend Physics, Anatomy and Psychology

The reason two equally pricey headphones can sound or feel different is that they distort things in different ways. When engineers build new headphones, they have to not just think about how human hearing distorts sound, however likewise the physical restrictions of any speaker.
If all the issues of speakers and ears werent enough, listeners themselves play a big function in deciding what makes for a “good” set of headphones. Eventually, the science of earphone style, the artistry of the material creators and the human experience all converge to form the perception of “excellent” headphones. Because when all the characteristics align, a great pair of earphones can give you the opportunity to be transformed by sound.

Headphone designers have to stabilize scientific limitations with human preferences.
What you like to listen to is also important for choosing the right set.
Between music, podcasts, video gaming, and the limitless supply of online material, most people spend hours a week using earphones. Perhaps you are thinking about a brand-new set for the holidays, but with numerous choices on the market, it can be difficult to know what to pick.
I am an expert artist and a professor of music innovation who studies acoustics. My work investigates the crossway in between the clinical, subjective and creative human aspects of noise. Choosing the best earphones involves thinking about all three of those elements, so what produces a really good pair?

Sound is just a series of low pressure and high pressure areas where air particles, represented by the small dots, compress or spread out apart. Credit: Pluke/WikimediaCommons
What is sound actually?
In physics, sound is made of air vibrations including a series of low and high pressure zones. These are the cycles of an acoustic wave.
Counting the variety of cycles that take place per second identifies the frequency, or pitch, of the sound. Greater frequencies suggest greater pitches. Researchers explain frequencies in hertz, so a 500 Hz sound goes through 500 complete cycles of low pressure and high pressure per second.
The loudness, or amplitude, of a noise is identified by the maximum pressure of a wave. The greater the pressure, the louder the noise.
To create sound, earphones turn an electrical audio signal into these cycles of low and high pressure that our ears analyze as sound.
The human ear is an intricate system that turns vibrations in the air into electrical signals that go to the brain. Credit: Iain/WikimediaCommons, CC BY-SA
The human ear
Human ears are unbelievable sensing units. The typical person can hear a huge variety of pitches and different levels of loudness. How does the ear work?
Your eardrum equates the air vibrations into mechanical vibrations of the small middle ear bones when sound enters your ear. These mechanical vibrations become fluid vibrations in your inner ear. Delicate nerves then turn those vibrations into electrical signals that your brain translates as noise.
Individuals can hear a range of pitches roughly from 20 Hz to 20,000 Hz, human hearing does not react equally well at all frequencies.
For instance, if a radio frequency rumble and a greater pitched bird have the exact same volume, you would in fact perceive the rumble to be quieter than the bird. Normally speaking, the human ear is more conscious middle frequencies than low or high pitches. Scientists think this might be due to evolutionary factors.
The majority of people do not understand that hearing sensitivity varies and, frankly, would never ever need to consider this phenomenon– it is merely how people hear. But earphone engineers certainly need to consider how human understanding varies from pure physics.
Speakers are essentially made of 4 components, a magnet (1 ), a coiled wire (2 ), a spring or suspension (3) and a diaphragm (4 ). Credit: Svjo/WkimediaCommons, CC BY-SA
How do headphones work?
Headphones– both larger ranges that sit over your ears along with small earbuds– are simply small speakers. Merely put, speakers do the reverse of your ear: They convert the electrical signals from your phone, record player or computer into vibrations in air.
A lot of speakers are made of 4 components: a stationary magnet, a wire coil that returns and forth around that magnet, a diaphragm that pushes air and a suspension that holds the diaphragm.
When the electrical signal of a tune or podcast pulses through the wires in a set of headphones, it alters the existing and moves the magnet. The magnet then moves the diaphragm in and out– kind of like a plunger– pushing and compressing air, producing pulses of high pressure and low pressure.
Ideally, a speaker would transform the electrical signals of the input perfectly into sound representations. The genuine physical world has restrictions. Things like the size and material of the magnet and diaphragm all avoid a speaker from perfectly matching its output to its input. This results in distortion and some frequencies being louder or softer than the initial.
While no headphone can perfectly recreate the signal, there are infinite different methods to select to distort that signal. The reason 2 similarly costly earphones can sound or feel different is that they misshape things in various methods. When engineers build brand-new earphones, they have to not only consider how human hearing misshapes noise, but likewise the physical limitations of any speaker.
What you like to listen to and how you like your headphones to sound play a huge function in determining what produces a good set of headphones.
Listener choice
If all the problems of speakers and ears werent enough, listeners themselves play a substantial function in choosing what makes for a “great” set of headphones. Aspects like age, experience, music and culture category choice all affect what sort of frequency distortion someone will choose. Earphones are as much a concern of personal taste as anything else.
Some individuals choose bass-heavy headphones for hip-hop music, while classical music listeners may want less frequency distortion. Music or leisure listening arent the only things to think about. Headphones for the hearing hindered may highlight frequencies from approximately 1,000 Hz to 5,000 Hz, as this helps to make speech more reasonable.
You might definitely play a hip-hop tune through earphones created for the hearing impaired, however the majority of people would concur that the outcomes arent going to sound excellent. Ensuring the headphones you pick match how you are going to utilize them goes a long way in determining what will sound good.
Ultimately, the science of headphone style, the artistry of the content developers and the human experience all converge to form the understanding of “excellent” headphones. Despite all these moving pieces, there is one sure-fire method to understand when earphones are good: choose a good tune and put a pair on! A great set of earphones can give you the chance to be changed by sound due to the fact that when all the qualities align.
Written by Timothy Hsu, Assistant Professor of Music and Arts Technology, IUPUI.
This short article was first published in The Conversation.