Are Headphones Considered Input or Output Devices?

by Alex.   Last Updated On July 17th, 2022.
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When it comes to understanding the differences in input and output devices, we first need to understand how the audio signals flow between an input and output device. For example, when you connect a pair of headphones to a computer or stereo, you are using them as an output device.

But, if you have headphones with a built-in microphone, and you are using that microphone to send your voice to a computer or laptop, your headphones are considered input devices while still retaining the ability to be use as output devices. This makes them combination input and output devices, also known as an IO device.

When used simultaneously to listen to music while also recording vocals, headphones are considered dual signal devices, and they can be considered an input or output device at either moment depending on how they are being used at that specific time.

The shortened term for this is an IO Device, IO being short for input output, and it is commonly used when referring to computer systems, aviation or naval communication headsets, and different styles of consumer headphones or headphone and microphone combinations.

To understand the differences in input and output devices even further, let’s dive in and take a closer look at the different ways an input device and output device send and received various sound waves and other digital data.

Table of Contents

Understanding Input and Output

When you hear the terms input device and output devices, you are most likely referring to how a computer is sending and receiving sound waves or other digital data.

These same terms can also be used for mixers, splicers, digital microphones, and countless other electronics or peripherals that deal with music, vocal recording, instrumentation, etc.

If referring to an input device, the main thing to keep in mind is that this device will receive digital data from another source and process them internally. So a computer system, laptop, or mixer connected to digital microphones microphone would be considered an input device.

Any device that can be used for converting analog audio signals can also be considered an input device, although devices such as analog converters can be input or output since they handle digital audio data in different ways.

A computer system, laptop, and mixer can also be considered an output device depending on how digital audio data is handled internally. This term is normally reserved for headphones, speakers, or other peripherals which are used to play sound so you can hear and enjoy it.

Additionally, when thinking about a computer system, other input devices can be the keyboard or mouse, as well as a scanner, webcam, or barcode reader. All of these devices are sending digital signals and other data to the computer in one way or another, so they are input devices.

Adding DACs Into The Mix

We can go even one step further and get slightly more confusing when we add DACs into the mix of input and output devices. A DAC or digital-to-analog converter is an inline audio interface that can be used as both an input device, as well as an output device depending on your needs at the time.

Some headphones and stereo systems, as well as some older model smartphones, will not function properly without a DAC somewhere in their connection path to help send audio signals. DACs are professional audio interfaces that work with a computer’s digital audio to output sound and other electrical energy in a way that headphones can highly benefit from.

Some headphones require a DAC in order to perform at their full potential, while most do not. Having a DAC as an inline output device for your headphones can improve the audio signals while reducing the amount of interference you hear in the line.

You can also add a separate DAC to a device that already has a built-in digital to analog converter. This is especially true with smartphones, where their sound cards already include a converter as well as an amplifier.

The quality is mass-produced, however, and will not be as high quality as an external digital to the analog converter you can purchase separately. When doubling up on a DAC, you can easily improve the quality of sound while reducing distortion, peaking, and background hissing.

DAC and headphones

How Headphones Handle Sound

Headphones in and of themselves are considered an output device of digital audio signals. Their job is to send out electrical signals that your ears can hear. Headphones receive audio signals from computer systems, stereo systems, smartphones, tablets, and a whole range of other large and small electronics.

Headphones are a form of transducer that collects mechanical wave energy from audio input devices, usually analog audio signals, and turns them into sound waves and appealing digital audio which is what reaches your ears.

However, if you were to take a closer look at the internal composition of headphones, they contain drivers which can be classed more as an input device. Headphones with these drivers can both receive and send raw audio energy to and from other sources. So they are ultimately both input and output devices.

Additionally, if we were to consider headphones that have a built-in microphone, the electrical audio signal of sound is output to your ears, while your voice or instrumentals are input to a processing device.

Headphones receive audio data from a computer system and push it to your ears, so they are output devices, but having the addition of a built-in microphone turns them into input and output devices.

How Devices Handle Sound

Headphone drivers are similar to the drivers you would find in other speakers to send audio signals to and from different sources, only on a much smaller scale. You will find almost identical wiring paths, with moving-coil drivers and dynamic drivers differing only in how the audio signals are handled.

When talking about headphones and their built-in microphones, it’s important to note that headphones themselves will receive alternative audio signals from a dedicated input device that are first received as digital or analog audio data, before returning it as processed data to your headphones or external speakers.

This audio input is handled by a computer system or stereo making them your input devices, and the audio output is managed by your headphones making them our output device. It’s not difficult to become confused with understanding whether something is an input or output device, especially when so many electronic items can act as both.

Moving coil dynamic microphones will react to the same sound waves as headphones do and will vibrate an internal diaphragm with help from an internal magnet. This hardware input device takes quite a bit more in-depth understanding to really grasp how the sound input is turned into output audio.

Both headphones and microphones can technically be considered dual IO devices with digital signals and sound waves, as they can both act as input and output devices. Headphones themselves with no other additions are output devices, while their attached microphones are external input devices.

Reversing the Audio Interface

With some tinkering, however, both headphones and microphones contain the right components to potentially be set up as their opposite. Each device has the same style of drivers, diaphragm, and magnetic coils to use electrical energy to change digital signals, they are simply laid out in a different manner.

In theory, reversing the wiring could turn your headphones into a sound recording device with input functionality, while your dynamic microphone diaphragm can be used as an output device for external audio.

The audio signal this reversal produces, if any, will not sound nearly as good as it should. This is due to how the exact line is laid out. While the components are the same, their layout is vastly different, and even reversing the wires, while potentially useful, will not produce the highest quality audio possible.

USB Devices for Sound Quality

Many audio components are being made to connect via USB in order to produce sound. These ports are extremely common on desktop computers, laptops, console devices, and even in modern vehicles. While a USB device is very easy to connect to, their return on sound can be lower quality than you expected.

One of the biggest differences is that a USB connection connects directly to each device. It plugs in quickly and easily, but USB does not offer the same connection as a 3.5mm brass jack would. In this case, audiophiles may notice distortion such as humming, buzzing, whistling, or even a shrill tone.

This distortion could be from the electrical energy passing through the USB, but could also simply be due to the lower quality of a USB connection in general. This lower quality could be on the side of the USB itself, or could be blamed on the device it is being connected to. Some USB ports can become loose over time leading to a less than optimal connection.

Despite this potential for lower audio output, many music lovers are turning to USB for the overall convenience it provides. It’s very much a plug-and-play type device that interfaces with a wide range of devices and in most cases, won’t need any additional hardware to work properly.

Headphones as DAC Output Devices

Headphone speakers of all types are considered transducer output devices, however, in order to work properly, they require analog audio signals they can process. Most modern headphones and almost all computers have a DAC included in the form of their sound cards.

However, some brands of headphones or speakers specifically made for audiophiles may require a DAC to be installed between the headphones and computer or stereo to get the best sound quality in return. In most cases, a DAC is only needed if you are a true purveyor of fine sound and high-quality music.

Reducing Distortion

For example, if you have purchased a higher-end pair of headphones but notice a lot of background hissing, static, or other distortion in your music, it may be due to low quality or improper conversion of the digital data into an analog format in your ears can hear.

This is where the DAC will come into play. Installing a DAC between your output device and your input devices can greatly reduce the amount of distortion you hear. For true audiophiles, having a high-quality DAC can clean up the sound and provide a clean and clear listening experience.

Almost all computers will use their internal sound cards as a DAC and amplifier, which means you won’t need to install an in-line unit. Most modern smartphones and tablets are the same. Stereo systems are where a DAC is more necessary, especially when it comes to higher-end brands.

External Smartphone DACs

You may also need to find a small DAC for use with older smartphones, such as some Apple iPhone’s that do not include 3.5mm jacks for headphones. These small DACs can be installed just after the lighting connector and before the connection of a dedicated output device.

These much smaller portable DACs are normally coupled with an amplifier, giving you less hardware to worry about when you just want good, clear, high-quality sound from your smartphone. Every smartphone will already have a DAC built-in, but the quality of these components is not as high as it could be.

If your device has an internal sound card and doesn’t need a DAC to play music or other sounds to your satisfaction, there is no reason you need to run out and get one. However, for audiophiles and other purveyors of good music, having a DAC in your system even with good quality sound cards can improve the input and output of analog signals through even mediocre headphones.

In Conclusion

On their own, headphones are generally seen as output devices. They are made to receive audio signals from a computer, smartphone, tablet, or other audio device and send it out to your ears.

When connecting your headphones to a stereo system, computer, or other audio devices always be sure to plug them into the output jack. Plugging your headphones into the input jack will give you some sound, but it will be extremely distorted, faded, and sound poor.

Headphones that have a built-in digital microphone are considered both an output and input device since they are now also receiving audio signals and sending them to another device for processing.

These headphones can still be plugged into the output jack on most computers, but will normally have a Y cable on the end for connecting into both the output and input jacks on a stereo system or DJ table.

The cables will be color coded, but in many cases the larger jack will be plugged into the socket for output devices separately, while the smaller jack for your digital microphone will be plugged into the input socket so the computer can receive raw external data.

If you have trouble telling the difference between both input options, consider looking online for your brand of stereo, DJ table, or other audio equipment to see which port on the audio interface is for input or output.