One very common musical exercise that I have noticed all the best guitar teachers recommend is to sing what you play. A lot of instrumental players tend to think that singing is for singers and that they don’t need to work on their vocal ability. The truth is that the ability to vocalize a melody is perhaps the strongest way to internalize and therefore control the way you will ultimately make it sound on your instrument. The more you practice singing, the more clearly you will be able to imagine the sound in your mind’s ear.
Whether you are a classical guitar player looking to better understand and interpret written music, or if you are a jazz or blues player looking to develop your ability to improvise melodies, a bit of singing should absolutely be part of your daily routine. Great musical improvisors like Thelonious Monk and Jimi Hendrix had been known to hum or scat what they were playing as they were playing it. So great was their internal sense of melody (and their command of their instruments) that they could just instantly realize these melodic threads as soon as they imagined them.
As far as classical guitar goes, many popular methods stress singing, particularly in the early stages. Aaron Shearer goes so far as to insist that beginners sing every note of every etude they are given in solfege and at tempo before so much as plucking a string. I’m sure that any of my students reading this are happy that I don’t stress singing as much as Shearer did, but we can also appreciate that this kind of thorough musical rigor leads to truly outstanding results.
Obviously, even with the Shearer method, the intention is not that every guitarist needs to develop a fantastic singing voice or an enormous vocal range. You just need to develop some ability to create and control the pitch of your voice. Once you’ve got that sense of control you can practice moving up and down via half steps and whole steps. Initially this type of practice will train your ears much more than your voice, which is precisely why music teachers stress the importance of this training specifically to non-singers.
In my experience, learning to sing scales and simple melodies has done wonders for my sense of intonation. I would even go so far as to say that I barely had any sense of intonation before I started vocalizing melody (it has improved my ears THAT much). I don’t go overboard with vocal exercise. I basically try to make sure that I spend at least 15 to 20 minutes a day singing what I am playing. Initially this meant that I just played one or two notes and practiced matching them in a vocal range that was very close to my speaking voice. Once I got up to the point where I could sing a complete C scale, I simply sang along as I did my normal scale practice.
Eventually, I learned to use the Solfege syllables (Do, Re, Mi, Fa, Sol, La, Ti, Do) so that I could keep track of the scale degrees and develop some sense of the intervals between them. After getting the hang of straight scales, I tried to sing simple arpeggios (Do-Mi-Sol-Do, Re-La-Fa-Re, etc). This improved my sense of thirds, fourths and fifths. It is also a good idea to try and play a note on your instrument and practice singing specific harmonic intervals above or below that note. You can start with 2nds, 3rds, 4ths and then eventually try to get a sense of all the intervals up to one octave. This really has helped me distinguish between intervals of chords that I am playing. It also really helps me to pin-point problems when my guitar is sounding slightly out of tune.
Currently, I am training under the fixed-Do solfege system. Which means that “Do” is only used to vocalize C natural, and therefore every major scale uses a different collection of solfege syllables. I used to use moveable Do, which is simpler to understand, but I want to see if the fixed Do can help me to hear the difference between specific tonalities. I am currently going through this obsessive phase ever since I read about the differences between “just” and “equal tempered” tunings and the smearing effect equal temperament supposedly has on certain tonalities. I want to know if I can actually perceive and appreciate these inherent tonal characters that others say exist.
So look, you don’t have to be the next Beyonce or Bublé, but you should learn to sing a bit simply because it will improve just about every aspect of your playing. Remember to keep it to just about 20 minutes a day and start very simply. If you are consistent you should experience a tremendous boost to your ear training in 2 to 4 weeks.