A metronome is a device that generates a regular sound to indicate beats. Older metronomes worked like old-fashioned wind-up clocks. A pendulum was powered by a wind-up spring, and a movable weight on the end of the pendulum determined the speed of the beat (tempo). Each time the pendulum swung all the way to one side it caused a loud, mechanical click.
Modern metronomes are usually battery powered and entirely electronic (no pendulums or any other moving parts). The tempo is set either by turning a dial or, more commonly, by entering digitally the desired number of beats per minute, and the sound generated is a short, electronic ping.
Many newer metronomes offer additional features. While not necessary for typical instrumental practice, these features can at times be useful. These include: subdivisions (eighths, triplets, or sixteenths) usually at a different pitch from the beat; playing a tuning note (some metronomes are built with a complete tuner in the same unit); visual cues such as flashing lights or an LCD display; and having the metronome determine your tempo by tapping a button.
Types of Metronomes
Metronomes come in a variety of shapes and styles. Smaller ones include credit-card shaped, wrist-watch, and cassette tape size. Larger metronomes are the size of a paper-back book or larger.
Each style has its advantages and disadvantages. Larger metronomes usually have a louder click and, often times, make a more percussive sound than the smaller models. This percussive sound is preferable because it usually stands in better contrast to the sound being made by the instrument, i.e., a more percussive click is easier to hear. Larger metronomes often offer more features, too. The Dr. Beat type, for example, has individual volume controls for each subdivision of the beat.
Small metronomes also have advantages. The credit-card type, such as the Seiko DM-20, is extremely portable. There is room for it in just about any clarinet case. Batteries last a long time in the small metronomes. My Seiko is close to 10 years old and has never needed a replacement battery! Larger metronomes use larger batteries that need to be replaced regularly. The credit-card type are also nearly indestructible. Mine has been dropped onto concrete floors dozens of times and is none the worse for wear. You wouldn't want to drop a Dr. Beat from a music stand onto a concrete floor.
I prefer using a smaller card-type metronome. The small size makes it easy to carry around inside my case, and the toughness means I don't have to worry about breaking it. They are also very inexpensive--about $25 for a Seiko DM-20 as compared to well over $100 for a Dr. Beat. It's usually most convenient to put the metronome on the music stand while practicing, and there again, the smaller metronomes prove more convenient.
There is one unfortunate feature of the DM-20 that should be mentioned. The controls are all flat areas (pressure-sensitive buttons) on the face of the unit. This includes the on-off switch. This switch has managed to get itself pressed at some rather awkward moments including the middle of a rehearsal and also while getting onto a plane (this can attract some alarmed looks). I usually remove the metronome from my case before going on stage to insure that it doesn't accidentally switch on during a concert.
Using a Metronome
So you decided on a model, brought it home and are ready to start using it. But how? Just turn it on and let it keep time for you, right? Not quite. Don't rely on the metronome to count for you. Instead, use it to check and correct your own sense of rhythm and tempo.
It's appropriate to use a metronome for a great deal of your technical practice. This includes scales, exercises, and any other difficult technical passages. For a particular passage, begin by experimenting with different tempo settings to find out exactly how fast you can play the passage with perfect accuracy and control. Most students try to hurry the process by settling on a tempo that is too fast. This is a great recipe for frustration and failure.
It is vital that you hold yourself to the highest standard and choose a tempo that you can truly handle well. Trying to work out a difficult technical passage by playing it over and over again at performance speed will yield disappointing results at best. At worst you may create a habit of mistakes or unevenness, i.e., a bad habit.
Once you have determined how fast you can play the passage well, decide which subdivision gets the beat. If your tempo is slower than about 70 beats per minute (bpm), you should probably use a smaller subdivision. For example, say that I am practicing a C major scale in a sixteenth note pattern. After experimenting, I find I can play it perfectly at 50 quarter notes per minute. However, 50 bpm is too slow to accurately keep time, so instead I decide to count eighth notes and double the metronome to 100 bpm. I'm playing the notes the same speed either way. At 100 bpm, though, as opposed to 50, there are a lot more metronomic guideposts to mark the way.
Next play through the passage five or six times with the metronome beating. If each time through sounds different, then the tempo is too fast. Slow down a few bpm and try again. If the passage sounded the same each time, and it sounded the way you wanted, then speed up the metronome by about 2 to 4 beats per minute. Try the passage another five or six times. Once again, if it came out even and controlled each time then advance the metronome another 2 to 4 beats per minute. If the passage was inconsistent, then return to the previous tempo.
Be creative in your practice, both with and without a metronome. Always bear in mind that you should not depend on the metronome to keep a beat for you. Use it to reinforce your internal sense of rhythm and help you notice spots in music where you get ahead or behind, or perhaps just feel ahead or behind. Then train yourself to feel those passages correctly by playing evenly with the metronome at slower speeds.
Metronomes come in a wide variety of shapes, sizes, price ranges, and feature sets. Decide which features are most important to you and get the model which comes closest to your needs. Many people, including me, are perfectly happy having an inexpensive credit-card type metronome like the DM-20. If you are in doubt about what to get, ask your teacher for advice, and also ask a music store clerk to demonstrate the features of various models.
Once you have chosen a metronome, develop a systematic method for using it. There are many different techniques that can be used to take advantage of a metronome in your practice, as well as several that are counter productive. The technique described above is fairly simple and makes a good starting point. From there, it will take thoughtfulness to use the tool well.