Sound hole

What it means

The sound hole is an opening in the top of a string instrument's resonating body. Through it, the sound generated inside the body can escape rather than remaining fully enclosed.

At the same time, the sound hole lets the column of air trapped inside the body act as a resonator of its own, further amplifying and coloring the sound.

In the notation

The sound hole has no notation of its own; it is a structural feature of the instrument, not a playing instruction.

Musical use

The shape and placement of sound holes differ greatly between instrument families: the violin and its relatives carry two curved f-holes on either side of the bridge, the guitar usually a single round hole, often decorated with a rosette, centered beneath the strings, and some mandolins or lutes have oval or ornamented openings.

The size and shape of the sound hole affect the frequency at which the enclosed air in the body resonates most strongly, known as the Helmholtz resonance, and so contribute substantially to the timbre and loudness typical of each instrument type.

The sound hole should be distinguished from the bell of a wind instrument: both let sound radiate outward, but the sound hole also sets an enclosed air column in the body vibrating, while the bell mainly shapes the direction and timbre of the air column already flowing through the instrument.

Performance practice

Take care not to accidentally cover the sound hole with a hand, arm, or stand while playing, since this noticeably muffles the sound. In recordings a microphone is often placed near the sound hole to capture the full body sound, though placing it too close can make the sound unnaturally bass-heavy.