How Do Auto-Tune Microphones Work? (Auto-Tuned Vocals Live)


Love it or hate it, the “auto-tune” effect is a pretty cool technological advancement in the field of audio, allowing vocalists to sing into a microphone and have they voices transformed into pitch perfect notes.

How do auto-tune microphones work? Well, there is really no such thing as an “auto-tune microphone.” Rather, the microphone outputs a mic signal which is then sent through an auto-tune processor (often in the form of a foot pedal). The processor is tuned to the proper key and setting and effectively auto-tunes the mic signals.

So even though there aren’t true “auto-tune mics” out there, it’s still worth understanding how auto-tune setups work with microphones, particularly in live settings. That is what this article will discuss!


What Is Auto-Tune?

Before we get into our discussion on auto-tune mics, it’s worth defining what auto-tune is.

What is auto-tune? Auto-Tune (first released in 1997) is a pitch correcting audio processor by Antares Audio Technologies. Many other pitch correction processors are on the market, though Auto-Tune is the proprietary eponym. Auto-Tune is used to alter the pitch of vocals and instruments (either subtly or obviously).

Auto-Tune and other auto-tune-like pitch correctors typically process audio by shifting the identified pitch to the nearest true semitone.

In western equal temperament, there are 12 equally divided semitones within an octave.

Auto-Tune first identifies the pitch the of audio signal. A single note of the human voice or of musical instruments generally has a fundamental frequency (the note being sung or played). Additionally, there are harmonics that sound at integer multiples of the fundamental frequency.

For example, a fundamental frequency of 100 Hz would have harmonics at 200, 300, 400, 500 Hz, and so on.

The processor identifies pitch by reading the frequency content of the signal and correlating the stronger frequencies to fundamentals and harmonics of a particular note.

Chords, which are made of multiple notes are difficult for Auto-Tune to process. That being said, processors such as Melodyne are fairly accurate at identifying the individual notes within a chord and are able to fine tune single notes within chords. That, to me, is really cool.

Once the pitch is defined, Auto-Tune will adjust it (up or down) to the nearest “true” note according to our equal-temperament 12-tone system.

Tuning Auto-Tune

Auto-Tune and other pitch correction plugins can be effectively “tuned.”

Being able to tune the pitch correction is incredibly important for different applications.

For example, there are two commonly used pitch systems in music. Though they are both based on the equal-temperament 12-tone scale, they differ in the fundamentals that relate to each note.

These tuning systems are known as:

  • A440: where middle A is tuned to 440 Hz and all other notes are tuned accordingly.
  • A432: where middle A is tuned to 432 Hz and all other notes are tuned accordingly.

Related article: Fundamental Frequencies Of Musical Notes In A=432 & A=440 Hz

Being able to tune Auto-Tune ensure its compatibility with the various tuning systems. We wouldn’t want to lock into A440 if the rest of the music in A432. That would mean that we’re tuning the vocal to be consistently sharp.

Additionally, these pitch correction processor can be tuned to certain musical scales. This is often when the “auto-tune effect” comes into play.

By tuning the processor to the key of the song, we can effectively make the vocal match the key regardless of how out-of-key the singer or instrument is.

However, when pushed too far, this will oftentimes remove the humanness of the performance, greatly reducing any vibrato or pitch ramping between notes.

This type of hard pitch correction distorts the voice but ensures that it’s in key. It is used to great effect in pop music (shout out to T Pain, an artist best known for his use of hard auto-tune).

Auto-tune (and other pitch correction processors) are available as both digital plug-ins for digital audio workstations (DAWs) and as rack-mount or pedals for real-time performances.

The “Auto-Tune Microphone”

As previously mentioned, there’s technically no such thing as an Auto-Tune mic.

Rather, any microphone can be used in conjunction with a pitch correction processor to achieve the “Auto-Tune” effect!


Using Auto-Tune In Studio Recordings

Auto-Tune is used in studio recordings all the time. This is particularly true in the clean production of pop music.

In most cases, Auto-Tune is used very transparently as a way to “touch up” a vocal and make it fit perfectly in the key of the song. I like to think of pitch correction, in this case, in the same way as enhancing a photo with Photoshop (without overly altering the content of the photo).

Studio Auto-Tune, when used in this fashion, is typically applied after the vocal performance has been captured by the microphone and recording console/software.

With Auto-Tune in a studio, a great vocal performance can be made perfect with little distortion or artifacts. Even to trained ears, subtle use of Auto-Tune can go undetected and sound as natural as the singer’s unaltered voice.

Of course, the Auto-Tune effect is also used in studio recordings.

In this case, the processor is typically engaged during recording.

The vocalists sings into the microphone. That signal is sent through the DAW (or analog console) with Auto-Tune engaged.

This means that, when monitoring, the engineer, producer, and artist will hear the vocal as if it was already processed through Auto-Tune. Again, this does not mean that the microphone, itself, is Auto-Tuned.


Using Auto-Tune In Live Performance

Let’s get outside of the studio and onto the stage, where pitch correction devices are also used on vocals.

In live situations, Auto-Tune-type processors are typically in the form of pedals (which can be controlled immediately by the artists) or in the form of rack mounts (which are controlled more so by the audio technicians).

The artist controlled pedals are typically used for the obvious Auto-Tune effect that has become popular in modern music.

These pedals allow the artists to control the amount and type of pitch correction that is applied to their voices, which could change for each song or even during a single song. These pedals also give the artist the ability to disengage pitch correction at any time, which comes in handy when talking to the audience between songs.

The Boss VE-500 (link to check the price on Amazon) is one such pedal that offers slight pitch correction, robotic autotune and everything in between. It also features many other vocal processes.

Boss VE-500

The rack-mounted pitch correction processors are often set transparently and are not adjustment much (if at all) after soundcheck. These units typically are used to polish vocals into the pitch-perfection with as little colouration to the vocal as possible.

The TASCAM TA-1VP (link to check the price on Amazon) is an example of a rack-mounted pitch correction unit with additional microphone modeling, compression, and equalization.

TASCAM TA-1VP

Do most singers use autotune? In modern pop music (and many genres), vocals are often processed with auto-tune or other pitch correction processors. Today’s pitch correction plug-ins are transparent and can change a well-performed vocal from great to perfect. They can also be hard-tuned to get the “auto-tune” effect as well.

Do singers actually sing in concerts? In pop music, there is sometimes debate as to whether a singer actually sings live or if they lip sync. Most vocalists sing in concert, though some do not. Though controversial, lip syncing can improve a performance, especially if the singer cannot reach the notes or if dancing is a part of the act.

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