How Do Wireless Headphones Work? Comprehensive Explanation

Wireless Headphones

Since the 1960s, wireless headphones have been a thing. However, the introduction of Bluetooth wireless headphones in 2004 completely changed the way people listen to music for personal use. Both amateur listeners and audio professionals quickly embraced this new technology. This article is for you if you’ve ever wondered how the audio from your device is played back by your wireless headphones or earbuds.

In this article, we’ll break down a recent technological innovation that enabled us to make the jump from wired consumer headphones to wireless headphones. How do wireless headphones work, and who invented the wireless technology that enables them to function? Let’s look more closely.

Wireless Technology

In order to understand how wireless headphones work, we’re going to need to know a little bit about wireless communications and technology.

Wireless communication is simply the transmission of information between a transmitter and a receiver using electromagnetic radiation. It has a history that dates all the way back to the 1880s. Most modern-day wireless technology sends information using radio and microwaves.

Radiofrequency (RF) waves and microwaves are a part of the electromagnetic spectrum, which encompasses all frequencies of electromagnetic radiation including visible light. RF and microwave radiation range from extremely low frequency (ELF) radio waves, which can have frequencies as low as 3 Hz, to extremely high frequency (EHF) microwaves, which can have frequencies up to a few hundred GHz.

 the electromagnetic spectrum

Radio and microwave communication transmits information from Point A (the transmitter) to Point B (the receiver) using two types of waves – the modulator and the carrier – in a process called modulation.

Modulation

We need modulation to make wireless headphones function. Modulation is a signal-processing method that involves two types of waveforms:

  • We call the first type the carrier wave. The carrier wave or carrier signal is usually a simple sinusoidal waveform.
  • We call the second type the modulator wave. The modulator wave is the signal that modifies some properties of the carrier wave and is the wave that actually contains the information we want to transmit.

This entire modification process is referred to as modulation. By modulating the carrier wave with the modulator wave, we can “encode” information into it and then transmit it through space at the speed of light.

There are many types of modulation. Each type explains what aspect or quality of the carrier wave is changed by the modulator wave. For instance, frequency modulation, also known as FM, is an analog modulation method where the frequency of the carrier wave is modified by the modulator wave. FM radio functions in this manner. The carrier wave frequency is the number of kilohertz that your car’s radio is tuned to.

FM and AM

We can see the analog modulation methods FM and AM in the animation above. The low-frequency modulator signal is modifying the amplitude of the carrier signal in AM (amplitude modulation) and the frequency of the carrier signal in AM (amplitude modulation).

Enter Bluetooth

Bluetooth is a wireless technology developed in the late 1980s as a means of connecting wireless headsets to mobile devices. Engineers at Ericsson Mobile first revealed their finished headset in 1999 at a tech conference. Throughout the early 2000s and 2010s, Bluetooth grew in popularity as one of the best wireless communication technologies for personal devices alongside WiFi.

Wireless Bluetooth Headphones

Armed with the basic knowledge of modulation and wireless technology we covered earlier, we can now attempt to understand how wireless headphones work. Bluetooth is the leading technology behind many modern wireless headphones and ear buds.

Bluetooth uses short-wavelength ultra-high-frequency (UHF) radio waves with carrier frequencies between 2.400 GHz and 2.485 GHz. It divides this range of frequencies into 79 separate frequency channels and chops up the signal into packets that get sent along the channels. Each packet gets assigned a random channel at a rate of 1600 times per second in a process called frequency-hopping. The frequency channel randomization is synchronized between the paired devices to the enable transmission and reception of the packets in the right order. This also prevents two unpaired devices from communicating with each other.

We use Bluetooth to transmit digital signals between devices when streaming digital audio. Wireless headphones work by receiving a digital audio signal comprised of bits – the building blocks of computer language that are either a 0 or a 1. An MP3 file is nothing more than a series of 0s and 1s. This sequence of 0s and 1s is sent from the transmitter (your smartphone) to the receiver (your wireless headphones) in the form of a modulated waveform.

Phase-shift Keying

Bluetooth uses a type of digital modulation called phase-shift keying (PSK) to encode digital information (0s and 1s) into a sinusoidal electromagnetic carrier wave. In this type of modulation, the parameter being modulated is the carrier wave’s phase. Phase is simply the position of the waveform in its cycle, from 0 to 360 degrees.

With PSK modulation, each bit or set of bits in a serial stream of data symbolizes a phase shift in the carrier signal. For instance, in quadrature phase-shift keying (QPSK), every pair of bits in the digital serial data steam is encoded into the carrier wave as a phase change. 0 0 is a 315º phase angle, 0 1 is a 45º phase angle, 1 0 is a 225º phase angle, and 1 1 is a 135º phase angle.

Once the digital signal is encoded into the electromagnetic carrier wave, it can be transmitted through space to the receiver, your wireless headphones, allowing them to work and deliver you streaming audio.

Demodulation & Digital-to-Analog Conversion

Your wireless headphones contain a receiver which accepts the Mobile phone’s Bluetooth carrier signal. Then, the headphones demodulate the signal back into 0s and 1s. The story is not over yet, though. In order for your headphones to actually play audio and make sound, they need to be fed an analog signal. For analog devices like speakers and headphones, digital bits of 0s and 1s have no significance.

To go from digital to analog, the signal must pass through a DAC, also known as a digital-to-analog converter. ADCs and DACs are found in many digital audio devices from audio interfaces to CD and DVD players. Once converted to analog, the signal drives the transducers of your headphones, producing the sounds your ears can understand, which is another fascinating process in itself.

Connecting Wireless Headphones to a TV, Radio, Or Other Device

It’s possible to pair two Bluetooth devices to connect wireless headphones to devices with ease.

By simply turning on the transmitter and receiver and setting them to the same frequency, we can connect devices that have other wireless connection options (RF or IR) wirelessly.

The devices will need to be connected to a standalone transmitter and/or standalone receiver if they don’t already have Bluetooth or another compatible built-in wireless system.

For starters, it would be ideal if we had wireless headphones with an integrated wireless receiver. The signal path can be made wireless in part by using receivers that wired headphones can connect to.

Fortunately, both RF and IR wireless headphones almost always come with a specific transmitter. This simplifies our problem by ensuring the transmitter can connect to our device (TV, radio, etc.) and makes it simple to connect the headphones to the transmitter.).

The transmitters will typically attach to the device using an analog connection, such as a left/right RCA audio out or 3.5mm TRS stereo out.

The Pros & Cons of Wireless Headphones

The discussion of wired vs. wireless continues below. wireless headphones, let’s quickly discuss the pros and cons of wireless headphones.

The pros of wireless headphones include:

  • Many of the common audio devices available today are compatible with the widespread Bluetooth standard, which is now used in the majority of new wireless headphones.
  • being free from an audio device’s cord.
    • Up to 10 m (32 ft) of the range is typically supported by Bluetooth (Class 2).
    • RF (at about 2.4 GHz) enables a range of 91 m (300 ft) or more.
    • With IR, the range is up to 10 m (32 ft).

The cons of wireless headphones include:

  • requiring batteries to operate, which must be regularly replaced or recharged.
    • Additionally, the battery of the paired device is depleted by the Bluetooth standard.
  • Due to the integrated receiver, amplifier, and possibly DAC, the price is higher.
  • Compared to wired headphones, it can be a little frustrating to connect quickly.
Wireless Vs. Wired Headphones

Wireless Vs. Wired Headphones

The names of wired and wireless headphones clearly distinguish them from one another. In contrast to wireless headphones, wired headphones receive their audio signals through wires or cables.

The other differences are summed up in the following table:

Wired HeadphonesWireless Headphones
Physically connect to headphone jacksConnect wirelessly to the audio source
Connect to external amplifiersHave internal amplifiers
Better audio connectionSpottier audio connection
Active or passiveAlways Active
May or may not require batteriesAlways requires batteries
Has wires and is bound to the audio deviceDifferent wireless standards have different distances from the audio source

I would also add that in order to allow for mobility during live performances, in-ear monitors for stage use practically have to be wireless.

Both wired and wireless headphones function similarly outside of these important distinctions. Both of them are adaptable and can be worn as headphones or earphones, closed-back or open-back, over-ear or on-ear, etc.) and can have any driver type.

The transducers/drivers are the essential parts of any pair of headphones. Both wired and wireless designs affect how audio gets to the drivers from the source, but neither affects the components of the transducer.

We appreciate your reading and trust you found today’s information to be interesting. Let us know in the comments if you have any additional queries!

Recap: How Do Wireless Headphones Work?

We covered a lot of complex information and theory here. I hope you don’t have a headache! Let’s do a quick recap on the subject.

  • Electromagnetic radiation travels through space as a sinusoidal wave with a given frequency, amplitude, and phase.
  • Wireless communication technology relies on the transmission and reception of electromagnetic radiation at varying frequencies.
  • We can encode information into radio and microwaves using a process called modulation.
  • Bluetooth uses modulated microwaves to encode and transmit digital information (0s and 1s) between two devices such as your wireless headphones and your smartphone.
  • Bluetooth uses a digital modulation method called phase-shift keying. A change in the carrier wave’s phase symbolizes a change from a 0 to a 1 or vice versa when transmitting digital data
  • Wireless headphones work by receiving the modulated carrier wave from your smartphone. They demodulate it into digital data (0s and 1s) and then convert the digital signal to an analog electrical waveform.
  • The analog waveform gets fed to your headphone drivers to produce sound.

Leave a Reply

Your email address will not be published.