Is a Microphone Input or Output?

We all use microphones on a daily basis. Whether you’re making a call on your phone, using your headphones to chat in a Zoom meeting, recording a podcast, or just recording something with audio.

But, have you ever stopped and just marveled at this tech marvel. Perhaps you’re looking into upgrading your gear and it’s come to the point where you really need to understand what you’re working with.

To really understand how the average microphone works, you need to understand the flow of the audio.

When you work with audio on a daily basis (or you’re just curious), you need to have a good grasp of the input and output systems on your devices.

Is a microphone input or output?

A microphone is an input device. This means it “takes in” audio information and sends (or input) it to your receiving device. This could be your computer, phone, or someone else’s device. When you use a headset with a microphone, you are using an input and output device as it can receive and play audio.

What is the difference between an input and output device?

The difference between an input and output device lies in their function. Input devices receive and transfer information to a device for processing. Output devices are able to interpret and reproduce that captured audio. These days most general devices have both input and output capabilities e.g. a phone or laptop, while specialized equipment focuses on one function.

Think of it this way an input device takes information “in” and sends it to a processor that then sends this information to an output device that pumps “out” the audio by reproducing the processed information.

Input devices are designed to only allow the intake of information/audio/data, while output devices can only reproduce that information.

If you have a dedicated input device like a recording microphone, then it won’t be able to output the information it takes in.

You’d need a separate device for that. If you have a dedicated output device, like a great set of speakers, they will only output audio that they receive.

There are, however, devices that can receive both input and produce an output. These are generally known as I/O (input/Output) devices.

Your computer and phone are two of the most common I/O devices on the market. There are also many apps that have made I/O conversion easy and super useful – like text-to-speech software.

You speak, the computer receives the audio through its input microphones and via the software, translates the processed data into text. 

Other functions of I/O devices are:

• Receiving an email and being able to send that to the printer for output.
• Hitting the keyboard keys and seeing text being put out on your screen.
• Taking a photo on your phone, the camera is the input device and the phone screen is the output device. The list is endless.

Examples of input devices

The actual input device is a piece of hardware. The hardware input device takes in data from an external source and has the ability to process and send that data to another device. This external input is sent to the internal processor and converted to raw data. This data has to be sent to an external processor before it can be interpreted by an output device.

The most common examples of input devices are:

• The Computer Mouse – The computer relies on the user to move the mouse, to generate spatial data. The mouse can’t move on its own, meaning it is an input device.
• The Keyboard – The keyboard accepts the input from the user (which keys you hit) and sends that input to the computer for processing and output. It cannot receive information back or do anything with it.
• The Webcam – The webcam takes in the image it receives and sends it to the computer. The webcam can’t output anything like a projector can, just like a projector can’t output sound unless it has built-in speakers, however, it would be better to use external ones, check out my other post on how to connect bluetooth speaker to projector.
• The Microphone – The external sound is a source of input that is received by the microphone and processed by the driver. The computer then interprets that data by either saving it as a file or sending it to an output device.

Examples of output devices

Output devices are pieces of hardware equipment that have the ability to output information into a form that we are able to interpret. The output can be in the form of text, visuals, or audio. It receives data from a source and is able to display or replicate that data in the way it was originally received.

The most common examples of output devices are:

• The Computer Monitor – Your screen receives data from your computer and then outputs the data in the form of text, images, or video on the screen. It doesn’t receive raw external data, nor can it transfer data.
• A Projector – When the projector receives data from the computer, it is able to display that data visually.  It cannot take any external data in or send data on to something else.
• Speakers – When your speakers receive audio data, they can interpret the data and convert it to sound. It can’t receive any sound like a microphone, but simply puts out what it received from the audio device.
• Headphones – similar to speakers, your headphones receive audio data and convert it back to sound. The speakers in your headphones can’t receive raw sound from outside and send it back to your computer. For that, you need an input device added to the headphones, like a microphone.

Why are microphones considered input devices

A microphone’s main function is to  convert sound waves into electrical signals via an acoustic-to-electric transducer. These electrical signals are then converted into digital audio data, which is then sent (or inputted) into a computer.

For a microphone to truly be an input device it has to be able to capture and send audio signals to a computer (or phone, or any other device).

Usually, this is done by  converting analog audio signals (AC voltages) to digital data that is compatible with a computer.

There are a few ways that microphones can be connected to a computer that will allow for analog-to-digital conversion. Each method has its own benefits and drawbacks:

• Digital microphone: Better known as a USB mic, digital microphones have built-in ADCs and convert sound to digital data directly. The USB connection connects directly to the computer.

One of the most popular examples of a USB mic on the market has to be the Blue Yeti (Amazon link). 

Most people, myself included, use it as a mic for conference calls, a home recording studio – think podcasting, and even gaming thanks to its supreme sound quality.

Blue Yeti USB Microphone

Benefits: The Blue Yeti is probably the best on the market and because there is a direct USB connection, the sound is great.

Drawbacks: The fine-tuning needs to be done on the computer, meaning you don’t have as much control.

• Audio interface (hub): Next, for those who want to take things a step further or perhaps you already have a mic, is the hub-style audio interface. Probably the next best thing to a full-blown studio. This powerhouse allows multiple microphone connections (depending on the design), meaning you can record yourself singing and playing an instrument with a dedicated mic for each audio input. There are also  multiple customizations that can be done directly on the interface, to get the best audio recording. The audio data is then sent to the computer via USB, Lightning, FireWire, Thunderbolt, etc.

There are a number of great Audio Interfaces available, but I really like the Focusrite Scarlett 2i2 Audio Interface (Amazon link) for its features and stylish design.

The lightweight design also means it isn’t the worst thing to carry around if you need to travel.

Focusrite Scarlett 2i2 Audio Interface

Benefits: An audio interface is typically used in a small-scale recording studio. It offers great customization features and excellent sound quality.

Drawbacks: You will need a separate microphone.

• Audio interface (adapter): While most won’t choose this as their primary audio interface, it is a great mobile option. It typically only comes with one input (for the mic), a basic converter, and one connection port to the computer (usually USB).

This option is great if you’re strapped for cash or just want something you can easily carry around with you.

I like the Shure X2U (Amazon link) because it’s a powerful tool that hasn’t let me down yet.

Shure X2U

Benefits: Similar to the function of the larger audio interface hub, the adapter is easier to transport and has plug and play functionality. Perfect for recording artists to have as a backup stashed in the bag.

Drawbacks: You still need a separate microphone and while the sound quality is great for an adapter, it’s never going to be an audio interface hub.

This just goes to show, while a microphone can be seen as an input device, it still needs to be able to send that data to the computer to be useful. How you choose to send that data will determine the overall sound quality.

Can a device be input and output at the same time?

So far, we’ve discussed input and output devices separately, and rightfully so, because for the most part, they are separate. A device can be both an input and an output device, but can any device be input and output at the same time? The answer is yes.  

Input/output devices

For a device to have both functions it needs to be able to receive raw data from an external source, or another device (input), as well as send data out.

Here are a few examples of input/output devices we use on a daily basis:

• The USB flash drive: Able to receive, save, and transfer data, the USB flash drive is the perfect example. When it receives data, it’s an input device and when we retrieve data from it, it becomes an output device.
• A rewritable CD or DVD drive: We can easily send data to these devices and retrieve it again.

Are headphones with a built-in microphone both input and output?

So if devices like CD’s and USB flash drives are both input and output simultaneously, where does that leave something like a headphone with a built-in microphone?

Headphones that are designed for listening to audio are output devices. However, when you add a microphone it gains the function of an input device. That means that it has input and output capabilities. While the speakers are separate to the microphone, the dual functionality is connected to one device.

So, even though the first headphones started with humble beginnings as output devices only, modern developments have given us headphones that can now take input and deliver an output.

Generally, the output will be alternative audio signals (like when you’re chatting to a friend or playing an online game with chat).

Are headphones without a built-in microphone input or output devices?

Do headphones without a built-in microphone have any input functionality then? Just think about it, we’ve all had those sucky airplane earphones, and yeah the first time I took a flight, I thought about taking them (don’t you judge me).

However, you soon realize 1) the jack is weird and 2) you can’t use them for chatting – they don’t have input functionality.

A set of headphones without a microphone are output devices ONLY. They receive audio signals from a computer source and output that into your ears. The way they are designed, they cannot take any input from outside and convert it to electrical signals.

There is however a hack that you could use to convert your speakers (headphone speakers could be a bit tricky, but who knows) into a microphone… just don’t try this on your best speakers.

Can I use a speaker as a microphone?

If you want to convert your speakers into a microphone, you technically can. It isn’t for the technically challenged, but hell, if it’s an old set of speakers and you’re just messing around, why not give it a go. To give you a general idea of how this work, consider the following:

Your speakers have a cone that vibrates to create sound. It is similar to the microphone diaphragm that vibrates when it receives sound and those vibrations are converted to electrical signals. By reversing the function of the speaker cone, you can create a speaker mic that will receive external audio.

You might be wondering how on earth would that work? Well, quite simple actually.

Even though speakers and mics look very different (all in the bid to capture and produce great sound), the inner workings (together with a bit of cheating on the wiring) can give you the same results.

If you’re dying to try this out, follow these instructions:

What you’ll need to use a speaker as a microphone:

• An old microphone (broken is fine)
• A wire cutter
• Electrical tape
• An amp (working)
• A speaker

Step-by-step guide on how to use a speaker as a microphone:

1. Start by cutting the actual mic off the cable –  you just need the cable with the output connector on the other end.
2. Strip the wire back a bit to expose the cables. You will see three inner wires.
3. Completely remove the protective covering on the red and black wires (about half an inch is fine). Add a bit of electrical tape to the white wire as you won’t be needing it.
4. Remove the actual speaker from the protective box.
5. You’ll see two pins on the speaker, the left is generally the positive terminal and the right negative.
6. Using pliers, connect the red wire to the positive terminal and the black goes onto the negative terminal.
7. Plug in your output connector to the amp and test out your new microphone!

Can microphones be used as speakers?

If it’s possible to convert a speaker into a microphone, what’s stopping us from converting a microphone into a speaker? Nothing really, but the output (due to the size of the mechanics in a microphone) might not be all that much worth the effort. And, trust me, there’s a bit more effort.

While mics and speakers are similar, they have reverse functionality, and mics are a bit more complex and they need to literally pick up external raw data and convert it to electrical signals. So, how do we give speakers this superpower?

The easiest way is to reverse the signal flow. You’d need a speaker cable connected to the mic and a converter.

If the mic uses a condenser you’d also need to make sure that a constant polarized charge is maintained on the diaphragm. Ribbon dynamics aren’t the best to try this experiment on as they’re pretty sensitive.

Overall, I’d probably suggest that you don’t try this at home. Chances of failure are pretty high.

So, while your mic can technically be used as an output device, they aren’t going to blow your socks off and it won’t be the easiest weekend project.

To conclude

Microphones are input devices. They receive external sound and convert it to electrical signals that can be sent through a computer to an output device. The output device can then either reproduce that sound or convert it to something else, like text.