How do bar lines help performers read musical meter?

In Western musical notation, bar lines are essential tools that help performers navigate musical meter by providing a visual framework for rhythm and timing. Their primary functions include:12

• Indicating Stress: Bar lines serve as markers for points of main stress. In standard metric articulation, the strongest accent typically falls on the first beat immediately following a bar line.13
• Defining Measures: They divide the staff into segments known as measures or bars. These segments represent equal units of time, helping performers organize the flow of the music into predictable groups of beats.214
• Reinforcing Meter: When used in conjunction with a time signature, bar lines clarify the rhythmic structure of a piece. While the time signature defines the number and value of beats within each measure, the bar lines provide the physical boundaries that allow a performer to track these groupings visually.13

By establishing these regular intervals, bar lines help musicians instinctively perceive the underlying pulse and maintain the intended metric pattern throughout a composition.14