Have you ever had trouble tuning to another instrument? If so, read on…
In any ensemble, big or small, all the instruments need to be in tune with each other. If not, no matter how skilled the players, the music will not sound musical.
Who Tunes To What?
All the players need to agree on a pitch reference that everyone can tune to. This can be an external source, such as a tuner, or one of the instruments.
If your instrument is tuneable, you can tune a note on your instrument by matching it to the same note on a tuner or other instrument. We do this by listening for a disturbance called beating.
If you have a fixed pitch instrument such as a piano, your instrument becomes the reference and others tune to you.
Note: On fretted string instruments such as guitar or bass, once you’ve tuned one string to an external reference you can play a fretted note on that string as the reference for the next higher string and progressively tune the other strings.
How to Tune To A Reference Note: The Difference Frequency
When two (or more) notes are played together their sound waves combine. This combination wave has a frequency which is the difference between the frequencies of the two notes.
If the two notes are identical, there is no difference frequency. The notes lock together and sound like one louder note.
If your note is almost but not quite the same pitch as the reference note, the individual frequencies take many cycles before they match. This results in a very low (slow) difference frequency. The closer to unison, the lower the difference frequency.
Here is a diagram of 2 notes of nearly the same pitch (blue and green). Up/down represents amplitude. We hear amplitude as volume.
The difference frequency is produced by the overall shape of the composite waveform, shown here in yellow.
Look at the composite (yellow) wave:
- where both notes go up or down together, the composite wave is taller/louder
- Where they oppose each other, the composite wave is shorter/quieter
- If they oppose each other by the same amount, there is silence
Over one cycle, the composite wave gradually shifts from loud to silent (or near-silent) and back, creating a pulse.
Beating
We can hear the difference frequency as a pulse known as beating or beats. When both notes match, there is no pulse. When they’re almost in tune, there’s a slow, gentle pulse, maybe only 1 or 2 Hz (times per second).
As you tune your note away from the reference, the pulse becomes faster and the beating effect becomes more noticeable. This happens quite quickly, so make gradual adjustments!
Note: once the pulse is faster than 20 Hz we can’t hear the individual beats anymore. Instead, we start to hear two distinctly different notes. By now we’ve gone way too far…
Tuning the other way, as you get closer to matching the reference, the pulse slows down, then disappears when you’re in tune.
Example
Here is an example using 2 synthesiser notes, starting off in unison. After a couple of seconds, one note drifts flat, then back to unison, then sharp, before returning back to unison. I have chosen this sound because, like an organ, the notes don’t decay.
In the above example, the note is only just over a quarter of a semitone out at the furthest points. By then we can hear that the note sounds distinctly out of tune.
Sharp Or Flat? Listen For The Beats
Note that the beating effect is the same whether your note is slightly sharp or slightly flat. The beating only indicates how far you’re out: faster means further out, slower means closer.
Method
As you adjust your note, listen to the beating. Is it getting faster or slower?
- If the beating becomes faster, you’re getting farther out of tune. Change the direction of your adjustment; tune the other way.
- If the beating becomes slower, you’re getting closer to being in tune. Keep going. When the beating is slow, adjust more carefully.
- When the beating is gone, the two notes will sound as one. Even with an electronic tuner, where the timbre of the reference is nothing like your instrument, the notes will feel like they’ve locked together.
If you’re not sure whether you’re sharp or flat, keep going in the same direction! Sooner or later it will either lock in because it’s in tune or the beating will have become fast and obvious enough to tell you that you’ve gone too far and you need to turn around.
Make slow, gradual adjustments as you listen.
Above all, don’t panic! If you make random adjustments you may end up tuning to a different note altogether, or you may end up going back and forth without ever reaching the note.
Stay calm, listen for the beating and stick to the method outlined above.
Plucked Strings Take Note
Beating is more noticeable when the notes sustain well. On many acoustic plucked string instruments, notes don’t sustain for long before they fade away.
One solution to this is to play repeated notes; each note long enough to hear the beating but not so long that they die down. For an acoustic guitar, once every 3 or 4 seconds should work. Instruments with a small body and nylon strings, such as the ukulele, have less sustain and you will need to play more frequent, louder notes in order to hear the beating clearly.
What Note Do We Tune To?
It doesn’t really matter what the note is, as long as everyone agrees. Different instruments find certain notes easier to play than others. Ideally, the note used for tuning is an easy note for all involved.
A 440 – Concert Pitch
It’s possible for a keyboard or tuner to play different notes for different instruments to tune to. However, the tuning process is much quicker and more straightforward if everyone tunes to the same note. This is particularly true for large ensembles such as orchestras.
The closest to a universal tuning standard is A 440 Hz, or just A 440, also known as concert pitch.
Lower instruments can match A in a lower octave. Beating works when tuning notes at different octaves just as it does in unison.
Are Instruments Always Tuned To Concert Pitch?
The short answer is no.
Over the centuries the tuning reference has varied considerably, both above and below the current 440Hz. Some ensembles specialising in period music will use the appropriate pitch reference for the era.
More generally, apart from digital instruments, fixed pitch instruments don’t stay perfectly in tune forever and may end up sharp or flat overall. All other players will need to tune by ear to make sure they are in tune with that instrument.
As long as everyone tunes to a common reference, it doesn’t matter whether it’s in concert pitch or not.
Note: Beating can also be heard when other consonant intervals like a perfect 5th or perfect 4th are out of tune. You can tune to these intervals in the same way as tuning to unison.
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