Why does one bow stroke sound full and clear, while the next one sounds thin, scratchy, or too loud? The violin’s tone is very responsive to three different factors that work together: bow speed, bow pressure, and contact point. If you change any of these factors, you will change the sound. When you are first learning to bow, the tone may be unpredictable because these factors can change easily. It helps if you don’t immediately try to fix an ugly sound by increasing bow pressure; instead, see if one of the three factors has shifted.
Bow speed refers to how fast you are moving the bow. In a given amount of time, a faster stroke uses more bow, while a slower stroke covers less bow. Try drawing a long stroke on an open A string at a comfortable pace, then draw another long stroke of the same length noticeably slower, without pressing harder. How does the sound change? Slower bowing requires careful control because the bow stays in the same place on the string for a longer time. If you grip the bow tightly or your bow pressure varies, you can cause the tone to break up.
Bow pressure is the amount of pressure you apply to the string. Not enough bow pressure can cause a weak, airy, or inconsistent tone. Too much pressure causes the string to fight against the bow, creating a rough, scratchy sound. There isn’t one single amount of pressure that will give you a good tone all the time. The best pressure will depend on your bow speed, your contact point, and whether you are closer to the frog or the tip. During open string practice, vary your bow pressure slightly, rather than suddenly pressing down into the string. You aren’t looking for one set pressure; you want to know how the violin responds to different amounts of pressure.
The contact point is where you draw the bow, between the bridge and fingerboard. In general, drawing closer to the bridge requires more precise control, while drawing closer to the fingerboard can be done with a lighter touch. If the bow shifts slightly over the course of a long stroke, the sound may change, even if you don’t feel like you’re doing anything different. Occasionally checking your contact point might explain some of the strange sounding strokes.
These three factors are easier to understand when you explore them individually. Pick one open string and draw several strokes at one contact point. Vary the bow speed, but keep everything else constant. Then, keep the bow speed the same and vary the bow pressure. Finally, maintain the bow speed and pressure, but vary the contact point by drawing closer to the fingerboard and then closer to the bridge. These differences may not sound great, but the idea is to tune your ear to the way specific physical changes affect the sound.
Problems typically occur when more than one factor changes simultaneously. For example, if you are bowing near the tip and slow the bow speed, the sound may become thin and you might push harder to get a better sound, but the bow also moves closer to the bridge. The sound will be scratchy, but you may have difficulty isolating the problem. To fix this, shorten the stroke, go back to one open string, check the contact point, and choose a comfortable bow speed. Draw several strokes at this comfortable level, without making any other changes.
Eventually, you’ll be able to listen more closely to the sound before it gets ugly. A note may start to sound airy, but there might be a few seconds before it starts sounding that way. Or the sound may start to get rough, but you might be able to hear a subtle, scratchy quality before it becomes harsh. Recognizing these small cues is helpful. Hearing these changes early on allows you to adjust the bow speed, pressure, or contact point while the stroke is still in progress, which is more productive than deciding after the fact that the sound was bad.
