A
metronome is a
clock, but is basically useless until students learn how to count.
As a piano teacher I have great experience with counting, and many would doubt that it is right at the core of music of almost any description. Ask yourself, what is the thing that gives movement to melody, that gives coordination to harmony--usually the right hand and the left hand, respectively.
I tell my older students music is timed durations of sound and silence, and the way to time them is by counting--to
become one's own clock. In my own history, I never really liked to use the metronome, because
se it never seemed to work: when I used it the beat was never steady; it would always speed up or slow down, and, as a student, I never understood.
As a teacher, the answer is quite clear: it was not the metronome that was changing tempo, it was me!
Until one's own clock works--until one can count, out loud, realiably, audibly--one will never be able to calibrate one's own time sense. If one's own time sense is not constant, how can it synchronize with anything external?
And the counting out loud bit, this is also hard for the student, regardless of age. I hear it everyday, the beats that are swallowed--sometimes literally as the student swallows because of nervousness, or dry throat, or figuratively, when a beat just mysteriously disappears. Or the student will complain that counting is confusing.
Pedagogy tells us that the problem is not the counting, but the student's sense of the beat, and if there is confusion while counting, the confusion is at a deep level.
Silent counting does not much assist in alleviating this very real problem for students, for what is not heard, but thought, is caught up in the same inadequate
time sense, and mental processes that are at the root of the problem.
When students, or their parents say they will use the metronome, I discourage them; too often have I witnessed the spectacle of such a machine clicking the beat merrily, will the student plays on, making the same errors of time, oblivious.
It is often a substantial emotional hurdle for the student, and the family, but progress, particularly in baroque music, like that of J.S. Bach, where the beat is paramount, is not possible.
So, I console students and family with the thought that all of us, students, parents, and teachers have been going through this since there have been keyboards, even before the piano was invented.
As a hardware solution to a software, or maybe wetware problem, metronomes have been around virtually as long as has the piano--almost as long as the delusion that machines can replace parts of people, and that what is left will still work.
Metronomes, however, do have some uses. They remember best what 100 beats a minute is, though I, and many students do, but it is a good reminder of how fast a piece actually is. And for the advanced student, it is an excellant tool to assist in the acceleration of playing--when the student can reliably calibrate his own internal clock.
So:
Count out loud, loudly!