The bar line, that thin vertical line separating one measure from the next. It has several important functions but it can also be a hindrance to smooth, fluid playing.
Bar lines have been used in music since the 15th century as a simple way to visually indicate the meter of music. We know meter as a repeating pattern of strong and weak beats. ¾ time, for example, has a strong first beat (as do all meters) followed by two weaker beats. The time signature tells us what the pattern is; the bar lines show us where the next repetition of the pattern begins.
From a musicology perspective, bar lines were a critical innovation. Until bar lines came into use, rhythms were notated by using different note shapes or additional symbols. The means of notating rhythms was evolving, but bar lines created a way to organize rhythm and delineate the patterns in a standardized way. Any musician could decode music written with bar lines just from the written page.
As an organizational aid for musicians, bar lines are powerful. They enable us to see the metric groupings, which we call measures or bars, at a glance. This can help us keep our place in the music - at least, if we are counting. Bar lines, and the increased awareness of the meter they promote, help us convey the rhythmic flow of the piece.
As helpful as bar lines are intended to be, some musicians find them an obstacle to fluid playing. They unintentionally pause at a bar line, halting the flow of the music. Instead of being just a marker of the beginning of the next metric unit, the bar lines become visual obstacles that stop the reading process. This can be the source of more significant problems, such as missing opportunities for smooth fingering or observing larger patterns that may make learning a passage easier.
Stopping or pausing at the bar lines can be an extremely difficult habit to recognize. Occasionally, bar line pauses will appear to be a different issue like trying to find a finger placement or read the notes of a chord. One telltale sign of a bar line problem is a very brief pause between measures that occurs regularly (almost like part of the rhythm) in a passage or a piece. Sometimes the pause is so regular that it becomes an extra beat in the measure. If the measures in a piece are short, the bar line pauses may only happen every 4 bars or so. In a piece with longer measures, perhaps in 9/8 or 4/4 with multiple notes in each beat, the pauses are likely to happen at the end of each bar.
How do you know if you are pausing at the bar lines? Your teacher will be able to tell you, or you can easily find it out for yourself by videoing part of your practice session. If you nearly always have trouble making your music flow, this may be a symptom of a bar line problem too. If you suspect you are pausing at the bar lines, your next step is to break the habit.
The first thing I have my students do is to listen to the melody of the pieces, usually phrase by phrase. Almost always the melody will span several measures and it is easy for most students to hear how the melody should flow. Singing the melody to create the sense of sustaining the breath for its duration is also helpful. When you try this, you may discover that the melody begins just before a bar line and ends in the middle of a bar as well. Then play the melody, singing it out loud or in your head. Don’t worry about the fingering; just create a smoothly flowing tune. Repeat these steps daily in your practice until you are certain you are playing the passage without bar line breaks.
Another good practice habit is to consciously look across the bar line for fingering connections. The music doesn’t halt at the bar line and in many cases the fingering doesn’t either. Making your fingering connect across the bar lines where appropriate will help avoid a bar line pause.
When you are practicing a passage by itself, out of the context of the piece, always start a beat or two before the passage begins and end a beat or two after, so that you are not beginning or ending at a bar line. This not only will help prevent a bar line pause, but it will help you make a seamless transition into and out of the passage when you put it back into the whole piece.
I have occasionally used this interesting experiment to help students understand the power of bar lines: