Guitar

Quantization


In digital music processing technology, quantization is the process of transforming performed musical notes, (which may have some imprecision due to expressive performance), to an underlying timing grid that eliminates this imprecision. The purpose of quantization in music processing is to provide a more beat-accurate timing of sounds.


The most difficult problem in quantization is determining which rhythmic fluctuations are imprecise (and should be removed by the quantization process) and which should be left alone.


Applying standard quantization onto your music does not always result into an improvement, especially if it's guitar music.


Listen to example below. Although the notes of the guitar riff are perfectly timed by the rigid quantization, it tends to feel robotic and programmed. The short length of the notes (1/32), doesn't help either.


We can still reap the benefits of quantization when making guitar music, but we have to make some adjustments. We can improve the riff by elongating the notes. The notes below have been made 1/16th long. This way, the reverb of the instrument bleeds over to the notes that follow. The example below will already start to sound a bit more natural.



To further enhance the quantized notes and reduce the robotic or programmed feel of the riff, we can adjust the velocity of the notes. The velocity value is a numeric representation of how hard the note was hit on the instrument. For example: the harder you hit a piano key, the louder the note. Velocity gives a musical score its dynamics.


A real guitarist will never hit each note with exactly the same velocity, all the time. If we program all our notes with exactly the same velocity, the song tends to get monotonous by lacking dynamic.


In the example below we will change the velocity to give the riff a more natural and rhythmic feel. The velocity will increase from low to almost maximal, to emphasize the high note and give rhythm to the riff.



To add some more realism we can further elongate these quantized notes (with about 1/64th), so they overlap with the beginning of the next note. This way the notes seem to string together. This emulates a more natural way of playing an electric guitar riff and makes the riff smooth out.


Many instruments tend to have a dead spot at the very beginning of a note. This is quite audiable with electric guitars. When striking a guitar string, the sound does not instantaneously start. The note takes a few milliseconds to get to its full swing and volume. If you quantize your notes, these tiny offsets can give the impression that the note is off beat (starting too late).


We can counteract this, by moving the note a little in front of the actual beat, by about 1/64th as can be seen in the example below.


If you listen carefully you can hear that the first note of each phrase is a little out of sync (too late) compared to the rest of the notes. Those notes were not repositioned.