You'll notice as you play that you can only get a pleasant sound out of the reed when you're using just the right amount of breath. Use too much and it sounds forced, and the reed also may stick at times. Use too little and it sounds weak and breathy — not the sound you're going for. Throughout this book you will practice exercises and riffs that are going to teach you about breath control.
Spending extended periods of time practicing breath control can be difficult if you have trouble breathing from asthma or other respiratory problems, or even if you have no respiratory problems at all. Be careful not to overdo it! On the plus side, harmonica playing has been shown to be an effective therapy for respiratory ailments, to the point where many hospitals now offer special harmonica classes.
Singers use a technique called diaphragmatic breathing. The diaphragm is a band of muscle just below your lungs. Try breathing deeply, putting your hand on your stomach and, using only your breath, see if you can make your hand move outward with your stomach. Feel it as you do, then expel the air slowly and deliberately until you feel you cannot exhale any more. Do this exercise three times in a row. When you're doing it correctly you will feel noticeably full of air, and if you practice this regularly you'll have more breath to control as well as better ability to control it. Many experienced players do this every time before they begin to practice just to wake up their lungs.
You might find as you're playing that you either run completely out of air, or your lungs become full from playing draw notes. This happens to everybody, but if you're aware of the problem, you can easily learn to avoid it. The way to do that is to take or expel little breaths right on the beat. Any of the beats of the measure will do for this, although you might find that the 1 or the 4 beats are best because they're naturally at the end of many phrases. The important thing is to do this between the phrases or ideas that you're playing, as opposed to interrupting a phrase to take or expel a breath.
When playing draw notes on the low end of the harmonica you might find the sound you're producing to be weak, muffled, or lower than the correct pitch. This is the result of choking the reeds by forcing too much air through them. To avoid this, reduce the amount of air you're using on the problem notes, and try adjusting your mouth and throat positions.
Most people breathe through their nose and mouth or just through their nose. Harmonica playing is an exercise in breath control, and if you are breathing through your nose you are not putting all of your breath into the art of playing. Learning how not to breathe through your nose while playing requires that you think about it while you play, at least until it becomes second nature. This is true for the diaphragmatic breathing as well.