Are Microphones Input or Output Devices?

Last Updated on August 24, 2021.

We all know that microphones are used to record audio, to perform at live shows, etc., but are they input or output devices?

In this article, I will go over if microphones are considered to be input or output devices, how input and output devices work, and microphones can be used as speakers, and more!

So, without further ado, let’s get started!

Are Microphones Input or Output Devices?

Microphones are input devices because they send information into a computer via an audio interface, which converts the analog audio signal into a digital one. However, USB microphones that have a built-in headphone jack also work as output devices since they receive information from the computer as well.

Let’s define what a microphone does: A microphone acts as a transducer, converting mechanical wave energy, i.e., sound waves, into electrical energy, meaning that it’s designed to output an electrical audio signal, but it’s not designed to receive any audio signals, but rather sound waves.

Depending on the type of microphone you’re using, it might require some additional electricity to work properly (Condenser microphones require Phantom Power, a form of DC voltage which polarizes the capsule). However, dynamic and ribbon mics can produce enough power on their own to output an audio signal.

Microphones are not designed to receive any sort of electrical input, but rather sound waves which move their diaphragms mechanically to create the electrical audio signal.

Let’s use dynamic microphones as an example:

Dynamic microphones use a wire coil, magnet, and a thin diaphragm to capture the audio signal. The diaphragm is attached to the coil. When the diaphragm vibrates in response to incoming sound waves, the coil moves backwards and forwards past the magnet, creating an electrical current which is then channeled out of the mic via its output.

This all happens because the diaphragm is being mechanically moved by the sound waves, which are then transduced into electrical current.

In short, here are two points to summarize how a microphone really works:

  • Microphones are Input Devices: Microphones send electrical data to another device (Audio Interface, recorder, etc.) which converts it into a digital format that then gets sent to a computer, essentially making them input devices.
  • Microphones only output electrical audio signals: Microphones transduce the sound waves into electrical audio signals which are then output via the microphone’s output connection and sent to an audio interface to be converted into a digital format. USB microphones already have a built-in audio interface, which means that they already output digital data.

What are Input and Output Devices?

Now that I went over what a microphone is and how it works, think it’s time to take a closer look at the difference between input and output devices and define what each of them does.

Input devices send information to another device, whereas output devices reproduce information coming from a device. It’s possible for a device to be both input and output: For example, an Audio Interface since sends digital data to the computer but also receives digital data back from the computer, converts it into an analog audio signal and sends that signal to the speakers to be reproduced.

Audio interfaces can do both Analog-to-Digital conversion and Digital-to-Analog conversion, which allows them to process the microphones’ signal and convert it into a “language” that the computer can understand and use, and vice versa, which is why they are considered to be both input and output devices.

On that same note, USB microphones already feature a built-in audio interface, which is why they can be connected straight into the computer without the need of a dedicated audio interface, making them input devices.

However, USB microphones are also output devices since they have a headphone jack that ends audio signals to your headphones, and all of this information is coming from the computer in a digital format and converted into an analog signal. So, essentially, USB microphones are also Input and Output devices, just like an audio interface.

Essentially, Analog-to-Digital conversion of a microphone signal can happen in a variety of ways:

  • Audio Interface: Audio Interfaces are designed to take the analog signal coming from a microphone, or any other recording gear, and convert it into a digital signal that can be recorded by a computer.
  • USB Microphone: USB microphones have a built-in audio interface, meaning that they can convert analog signals into digital data, which can then be recorded by a computer.
  • Mixer: USB mixers generally feature a built-in audio interface, which allows you to record to a computer.
  • Adapter-Style Audio Interfaces: Adapter-style audio interfaces take an analog mic signal, convert it into a digital one and send it to the computer. Where they differ from regular hub-style audio interfaces is that they don’t do digital-to-analog conversion, meaning that they can’t output audio to a speaker system.

Now, if we follow this logic, then microphones are clearly input devices, while something like speakers or headphones are output devices, even though microphones and speakers work almost identically (only in reverse). Let’s take a deeper look into that, shall we?

Can a microphone be used as a speaker?

Like I just mentioned, microphones and speakers share a very similar design, especially when we compare speakers to dynamic microphones (the ones with a moving coil), since dynamic microphones use a wire coil, magnet, and a thin diaphragm to capture the audio signal. The diaphragm is attached to the coil.

When the diaphragm vibrates in response to incoming sound waves, the coil moves backwards and forwards past the magnet, creating an electrical current which is then channeled out of the mic via its output.

A speaker also has a large coil of conductive wire in it; however, it receives electrical audio signals and converts those into sound waves as AC voltage is sent through the conductive coil, causing electromagnetic induction to move/vibrate the coil within the magnetic field, which pushes and pulls the loudspeaker’s diaphragm.

This is why I mentioned earlier that speakers work just like microphones, only in reverse, since they have very similar components and work the same way, only the other way around.

However, this doesn’t really answer the full question, so let’s see if you can actually use microphones as speakers:

  • Can you use microphones as speakers? Since microphones work the same way as speakers do, just in reverse, reversing the signal flow should allow the microphone to reproduce sound (connecting it to the output jack of your computer, for example), but microphones aren’t designed to reproduce audio and will have a bad sound quality.

Can Speakers by used as a Microphone?

Like I just mentioned, speakers and microphones work in an almost identical way, but in reverse, and if you can use a microphone to reproduce music, you should be able to use a speaker to pick up audio, right?

You can use a speaker as a microphone by wiring it up so that the signal flow gets inverted, and it will work exactly like a dynamic microphone. However, since speaker diaphragms are usually much bigger than the one on microphones, they will pick up a lot more low end and very little high end.

FAQs

Can a microphone work without an amplifier? Microphones don’t need any external power to be able to output an audio signal (except for active microphones), but they can’t output a high-enough signal on their own and require an amplifier to amplify their signal to a usable level.

Can a microphone be connected to an iPad? You can connect external microphones to an iPad either by using a plug-n-play iOS compatible microphone that plugs directly into the iPad or iPhone, or you can use a regular USB microphone, connect it to a USB hub and use a lightning to USB cable to connect the USB hub to the iPad.

Can a mic be connected directly to a speaker? A microphone can be directly connected to a speaker as long as it’s an active speaker, since a preamp will be needed to amplify the microphone’s signal to a usable level. Passive speakers require an external amplifier or powered mixer.

Do ribbon mics need phantom power? Most ribbon microphones do not require phantom power to work, in fact, it’s recommended to turn it off when using ribbon microphones since it could damage them. However, there are some ribbon microphones that do require phantom power, but make sure that they do when turning it on to avoid harming them.

Conclusion

Microphones are input devices since they send information to another device, such as an audio interface, which in turn sends it to the computer, and USB microphones can be both input and output devices since they can also send audio to the headphones via their headphone jack.

If you found this information to be helpful, consider sharing it with someone who might find it useful!

Have a great day!

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