What is vibrato?

Vibrato in plain English

Watch a violinist hold a long note and you'll see their left hand rocking back and forth on the string. Each rock makes the string a fraction shorter and then a fraction longer, so the pitch of the note rises and falls a little around where it's written, over and over. A trained singer does the same thing with the muscles of the larynx. The result is a note that seems to glow, where a note held dead straight can sound plain and lifeless.

That wobble is vibrato, and it has two measurements. The rate is how many times a second the pitch goes up and back down, given in hertz. The depth, which voice researchers call the extent, is how far the pitch moves either side of the note. Depth is measured in cents, where a cent is a hundredth of a semitone, so 50 cents is a quarter of a tone.

In a mix, you can add vibrato to a sound that doesn't have any. On a synth that's done by pointing an LFO at the oscillator pitch. On recorded audio it needs a vibrato effect, which works with a short delay, and that is what the lab at the top of this page is running.

How does a vibrato effect work?

Recorded audio has its pitch baked in, so to bend it you have to play it back slightly faster or slower. A vibrato effect does that with a delay line only a few milliseconds long. The sound goes in one end and comes out a moment later, and an LFO keeps changing how long that moment is.

While the delay is getting longer, the sound coming out is being stretched, so it plays slightly slow and slightly flat. While the delay is getting shorter, the sound is being squeezed and plays slightly sharp. It's the Doppler effect, the same thing that drops the pitch of an ambulance siren as it drives past you, and it means the effect can move the pitch without a pitch shifter anywhere in it. None of the dry sound is mixed back in, so you hear only the copy, and its pitch is the one thing that has changed.

One detail catches people out when they look at the lab. The LFO screen draws the delay time, and the pitch follows how fast the delay is changing. So the pitch is at its highest where the delay line on the screen is falling most steeply, halfway down a slope, and back on the true note at the top and bottom of each curve, where the delay stops for an instant and turns round.

How much the pitch moves

Because the pitch follows the speed of the delay, rate and depth multiply. If the LFO swings the delay A seconds either side of its centre at f hertz, the fastest it changes is 2π × f × A seconds of delay per second of sound, and the pitch moves by that fraction.

Take the lab's vibrato at 10% depth, which swings the delay 0.5 ms either side of 6 ms, running at 5 Hz. That's 2π × 5 × 0.0005, which comes to about 0.016, so the copy runs up to 1.6% fast or slow. In cents that's about 27, a little over a quarter of a semitone.

You can run it backwards to set a vibrato by numbers. Say you want 50 cents at 6 Hz. Fifty cents is a pitch ratio of about 1.029, so the delay has to change at 0.029 seconds per second, and 0.029 ÷ (2π × 6) gives a swing of about 0.78 ms either side.

A vibrato under about 15 cents is subtle enough to read as warmth more than movement. Between about 20 and 50 cents it's a clear, singing vibrato. Past 60 cents or so it's wide and dramatic, which suits an operatic voice and very little else in a pop mix.

The table also shows something that surprises people coming from synths. On a delay-based vibrato, turning up the rate makes the pitch swing wider as well as faster, because the delay has to move the same distance in less time. On a synth's pitch LFO, the depth is set in cents directly, so rate and depth stay independent.

Reading the lab

The lab opens on the lead loop with nothing on it. The cards along the top switch between the dry sound, the vibrato, a chorus and a tremolo, and each card keeps its own settings, so you can move between them without losing anything. With the lab selected, the keys 1 to 4 do the same.

Under the wide screen, the LFO screen draws the delay over a short window either side of the moment you're hearing, with a dot riding the curve. The spectrum next to it shows the frequencies at the playhead, before and after the effect. The last panel, headed with the effect's name, is measured from the loop as the lab renders it: the pitch movement in cents, the range the delay travels in milliseconds and the correlation between the left and right channels.

The wide screen across the top compares the sound after the effect with the original, with time running left to right and frequency up the side. Vibrato with no dry sound mixed in leaves it almost even, because nothing is being cancelled. Turn the mix down and the copy starts to interfere with the original, and a faint, moving texture appears.

Feedback is switched off on this page, since a vibrato has none. Every card plays at the same loudness as the dry sound. You can also upload your own sound or record eight seconds of one, and nothing leaves your device.

The controls

Vibrato effects have fewer controls than most modulation effects. The Boss VB-2 pedal has rate, depth and a rise time. Ableton Live's Chorus-Ensemble has a Vibrato mode, and Logic Pro has Scanner Vibrato, modelled on the vibrato of a Hammond organ.

Rate

Rate is the speed of the LFO in hertz. For anything meant to sound like a singer or a player, stay between about 4 and 7 Hz; 5 to 6 Hz is a sensible default. Slower than about 3 Hz, the movement stops sounding like vibrato and starts to sound like a slow warble, the kind a worn cassette makes. Above about 8 Hz it turns into a fast, nervous flutter.

The lab rounds the rate to a whole number of cycles per loop, so the screens and the sound stay lined up. On the 8 second loops that means steps of 0.125 Hz. Live vibrato isn't usually synced to the tempo, because players don't lock theirs to the beat, but a tempo-synced rate can suit a synth part that's meant to sound mechanical.

Depth

Depth sets how far the LFO swings the delay. In the lab every 10% adds 0.5 ms either way, up to 5 ms at 100%, which at 5 Hz bends the pitch by about two and a half semitones. Plug-ins usually show depth as a percentage with no time attached, and one plug-in's 20% can move the pitch much further than another's, so set it by ear and treat the table above as a guide to the lab only.

On a synth, depth is normally in cents or semitones. A good starting point is somewhere between 10 and 30 cents for a lead, and less for a pad.

Mix

A vibrato runs at 100% wet. As soon as some of the dry sound is mixed back in, the moving copy and the unmoving original play together at slightly different pitches and beat against each other, and the result is a chorus, or with a delay as short as the lab's 6 ms, something close to a flanger. Some plug-ins have no mix knob for this reason. If yours has one and the vibrato sounds thick and swirly when you expected a clean wobble, check that the mix is all the way up.

Spread

The lab's Spread control moves the left and right LFOs out of step, up to half a cycle apart at 100%. One side then goes sharp while the other goes flat. On headphones that sounds wide and slightly disorientating. On speakers each ear hears both sides, so some of the beating of a chorus comes back. Most vibrato is kept in step on both sides.

LFO shape

Delay-based vibratos usually default to a sine wave, for a reason that follows from the maths above. The pitch follows the slope of the delay, and a triangle wave has two slopes, one up and one down, with a sharp corner between them. Put a triangle on the delay and the pitch jumps between one sharp note and one flat note, with nothing in between. A sine has a slope that changes smoothly, so the pitch glides.

Synths are the other way round, because their LFO moves the pitch directly. A sine or a triangle on a synth's pitch both give a smooth vibrato, and a square gives a trill between two notes.

Delay and rise time

Singers and players rarely start a note with vibrato. They land on the pitch straight and let the vibrato grow as the note is held. Effects copy this with a delay before the LFO starts, a fade-in, or both. The VB-2's rise time knob sets how long the vibrato takes to reach full depth after you press the switch, and most synths have an LFO delay or fade parameter that does the same for each note.

Vibrato, chorus and tremolo

These three get confused because an LFO drives all of them. Vibrato moves the pitch. Chorus mixes that same kind of moving copy with the original, so it's vibrato plus the dry sound, and the chorus lesson starts from exactly that. Tremolo leaves the pitch alone and moves the volume.

The Hammond organ shows the first relationship on its front panel. Its scanner vibrato has six settings. V1 to V3 are vibrato at three depths, and C1 to C3 mix that same vibrato with the dry organ, which Hammond calls chorus.

The tremolo vs vibrato comparison puts the two side by side, and the rotary speaker lesson covers the Leslie, where a spinning horn moves towards you and away from you and makes a real Doppler vibrato.

Vibrato, tremolo and the whammy bar

Guitar gear uses the two words the wrong way round. The arm on a Stratocaster bends the pitch of the strings, which is vibrato, but Fender named the bridge the Synchronized Tremolo. Fender amps such as the Vibrolux and the Deluxe Reverb have a control labelled Vibrato that pulses the volume, which is tremolo. Bigsby, at least, calls its arm a vibrato.

The mix-up is still printed on gear today, so when a guitar or amp control says one of the two words, listen to whether the pitch or the volume is moving before you trust the label.

Vibrato on a synth

On a synth, vibrato is an LFO routed to the pitch of the oscillators. Nearly every synth can do it, and on many hardware keyboards the mod wheel brings it in, so the player can add vibrato only where they want it and let it come and go with the phrase, the way a singer does.

In a DAW you can get the same thing by automating or mapping the LFO depth. A delayed LFO that fades in over 300 to 500 ms after each note starts is a quick way to make a programmed lead sound played, since short notes stay straight and only the long ones pick up vibrato.

Using vibrato in a mix

Vocals

Most singers already have vibrato, so the job in a mix is usually to leave it alone. Trained classical singers sit at around 5 to 7 Hz, often with a wide extent that holds through the whole note. Pop singers often start a long note straight and let a narrower vibrato in towards the end. If a vocal needs more or less, a pitch editor that works note by note will sound far more natural than a vibrato plug-in across the whole track.

Strings and leads

Sampled and synthesised strings can sound static without some vibrato, and many string libraries have a vibrato control for that reason. A delayed vibrato on the held notes of a lead synth is a common way to make it sound played. Pick Strings in the lab to hear it on a sustained part.

Guitar

Guitarists make vibrato with the fretting hand or the arm. A vibrato pedal gives a perfectly even wobble that no hand can match, which sounds deliberately artificial, closer to a warped record than a player. Try Guitar or Nylon guitar in the lab.

Lo-fi and tape wobble

A slow, uneven pitch drift is one of the signs of old tape and vinyl. Engineers call the slow kind wow and the faster kind flutter, and lo-fi plug-ins recreate both; XLN Audio's RC-20 Retro Color has a Wobble module for this. A slow vibrato of 0.5 to 2 Hz with a little depth gets you part of the way there, and you can hear it in step 4 of the lab. Real tape wobble is less regular than a sine wave, which is why the dedicated plug-ins add some randomness.

How to add vibrato, step by step

1. Pick the part and the notesVibrato suits long, held notes. If the part is mostly short notes, it will hardly show, and you may only want it on a few of them.
2. Set the mix to 100%On a vibrato plug-in, make sure none of the dry sound is mixed in. If it is, you'll hear chorus.
3. Start at 5 to 6 Hz with very little depthThen raise the depth until the wobble is just audible on held notes.
4. Adjust the rate for the feelSlower is calmer, and faster is more intense. On a delay-based vibrato, lower the depth a little as you speed it up, or the pitch swing grows too.
5. Delay the onsetUse the LFO delay, a rise time or automation so the vibrato arrives after the start of each note.
6. Check it against the other partsPlay the full mix. If the part now sounds out of tune against the chords or another melody, the depth is too high.

Starting settings for common sounds

These are places to begin. The lab depth figures assume a rate close to the one in the same row, since the pitch swing depends on both.

Common vibrato mistakes

Too deep

The wobble that sounds expressive on a part played alone can sound out of tune once the chords come in, because the ear keeps comparing the moving note with the steady ones around it. Set the depth with the whole mix playing.

Vibrato on every note

A plug-in vibrato moves short notes as much as long ones, and nobody plays that way. Delay the onset or automate the depth, so the vibrato only shows on the notes held long enough to carry it.

Leaving the dry sound in

If a vibrato sounds thick and swirly, the mix is probably below 100% and you've made a chorus or a flanger. Step 6 in the lab lets you hear the difference.

Speeding it up without backing the depth off

On a delay-based vibrato, doubling the rate roughly doubles the pitch swing. When you want a faster vibrato that moves the same amount, lower the depth as you go.

Training your ears to hear vibrato

The quiz under the lab plays the current sound through either a vibrato or a tremolo with random settings, with the screens covered and the loudness matched, and you say which one it was. The two can sound alike at the same rate, so listen for whether the note itself is moving up and down or only getting louder and quieter. A held note in the Strings loop or the sine makes it easiest. Eight rounds take a few minutes, and your best score is saved in your browser.

Questions people ask

Keep going