How headphones work is a complicated question that people have for a variety of reasons. The reason is that headphones have been around for decades, and you’d be surprised how much technology has changed in such a short period.
As it turns out, there are many more than just earpieces in most headphones. With all this technology, it can be hard to understand precisely what happens in these devices.
In this blog post will discuss how headphones work and their technology.
A bit of headphone history
Headphones are a relatively modern device, but they have evolved significantly over time.
The first model of this invention as we know it today is attributed to the German company Beyerdynamic in the late 1930s. It was also the first company to sell headphones to the general public in 1937 with the DT48 model.
With the advancement of electronics and the emergence of personal audio systems such as portable radios, Discman, iPods, and smartphones, their use has become widespread and extended to all audiences.
How does the human ear work?
Before explaining how headphones work, we must know how our ears work and how we interpret sound.
The air vibrates when a sound is produced, creating a sound wave. Our auditory pavilion (known as the ear) captures this wave and is directed to the ear canal.
At the end of this ear canal, we have the eardrum, a thin membrane connected to the chain of small bones (hammer, anvil, and stirrup) that amplify and transmit vibrations to the inner ear.
Finally, in the inner ear, a fluid stimulates nerve endings known as hair cells. These send electrical impulses, through the auditory nerve, to the brain. The brain receives these impulses and decodes them, giving rise to the phenomenon of hearing.
Operation of the headphones
Since we know how we interpret the sound we receive from the outside, we will explain how sound is produced in our headphones.
To facilitate the explanation, we will propose a simile with a drum since sound waves are produced very similar to those produced by headphones when hitting a drum.
When a drum is struck, the drum’s skin vibrates, creating sound waves. In headphones, the drum’s skin would be the diaphragm (paper, fabric, or plastic) that stretches through the cone of the headset. The cone is the shape of the headphones inside.
A magnet’s iron coil is at the earpiece cone’s smaller end. The coil is connected to the cables of the headphones that reach our sound source (mp3, smartphone, TV, etc.). The sound from the source is an electrical signal that converts the coil into an electromagnet.
The electrical signal from the source is alternate, which means that the magnetic poles of the coil will change from north to south and vice versa according to the received electrical signal.
These polarity changes cause the coil to attract or repel the magnet behind it, producing a back-and-forth movement. The coil is connected to the diaphragm and pushes and pulls it pumping sound waves as it happens in a drum.
How do the headphones work?
Bluetooth headphones are no different from wired headphones, except for how they receive and send audio to drivers or transducers.
Headphones function as transducers that convert electrical signals into sound waves. This is true for wired and wireless headsets. The headphone drivers are the transducers. They convert audio into sound; therefore, the essential elements of headphones are a pair of drivers.
Wired and wireless headphones use a technology known as electrodynamic transducers to send an analog audio signal through the drivers. This causes a proportional movement in the diaphragm of the drivers.
The diaphragm movement moves the air to produce sound waves that mimic the AC voltage shape of the audio signal.
This action is necessary, no matter what type of driver the headphones integrate. That said, the most common is the dynamic type.
What is Bluetooth technology?
Bluetooth is a communications protocol developed in 1994 to enable communication between mobile devices so that voice and data transmission would be possible without cables.
Bluetooth devices communicate with each other by radio frequency. For communication to be possible, both devices must be within their coverage range, which refers to the meters of separation between the two devices without compromising the stability of their connection.
Since its appearance, Bluetooth developers have been working on its continuous advancement. Thus, the different technological improvements materialize in the “Bluetooth versions.” With each new version, it works mainly in these four areas:
- Improve transmission speed. To get devices with lower latency.
- Increase the reliability and stability of the connection.
- Decrease energy consumption.
- Increase the range of coverage or reach.
Bluetooth versions are numbered from the first one that came out, “Bluetooth 1.0”, until the last version that hit the market in January 2020, “Bluetooth 5.2.”.
The version it incorporates must appear in the manufacturer’s specifications whenever you buy a Bluetooth device.
This technology was initially developed in 1989. However, the first official version was released in 1999. The directors who develop this connectivity improve it constantly and release new versions periodically.
New types of Bluetooth improve range, transfer speed, and power consumption. New wireless headphones use version 5.0 or later. However, they can work perfectly with audio devices that have version 4.2.
Bluetooth headphones how they work
Bluetooth headphones receive audio signals via Bluetooth technology, which is why they must be paired or wirelessly connected to an audio device to work correctly.
When paired, a Bluetooth audio device and headphones form a Piconet in which the device can effectively send audio signals to the headphones via Bluetooth. Likewise, when paired with a smart function-equipped pair of headphones, such as those equipped with voice control and playback capability, the audio device can receive information via the network.
After the headset’s Bluetooth receiver picks up the audio signal, it must pass through two key components for the drivers to do their job.
After receiving the signal, it must be converted to an analog signal. This is done through the integrated DACs.
The audio is then sent to a headphone amplifier so that the signal reaches a voltage level that can effectively drive the drivers.
A new, smaller type of headphones has become more common: noise-canceling headphones. They were invented by Amar Bose, founder of the Bose Corporation when he became frustrated with the noise of an airplane distorting what he was playing through his headphones.
Passive noise-canceling headphones use circum-aural (over-ear) padding and high-density foam to prevent ambient sound waves from reaching your ears.
Active noise-canceling headphones use a different method: The headphones emit sound waves to mask low-frequency sound waves from ambient noise, using a technique called destructive interference.
By emitting sound waves that are mirror images of ambient sound waves, noise-canceling headphones allow you to listen to the audio content you want and filter out another unwanted sound.
The basic idea behind headphones is that each ear gets its miniature private concert, primarily isolated from outside noise.
With this design, sound doesn’t bleed between the speakers in a pair of headphones, which lets people listen to their music without disturbing anyone else.
It also means those wearing headphones can hear the full range of audio frequencies, including deep bass lines on the low end and high-pitched vocals or screeching guitar solos on the high end.
We hope you enjoyed this article. The technology and science surrounding headphones are always fascinating, and I try to share them with you as much as possible.