Tighten the string
If that instrument has a pickup (with divided magnets) the output of a specific string can be increased by increasing the height of the magnet directly unter the string.
In stringed musical instruments, sound is created by plucking, strumming, striking, or bowing across a string in order to make it vibrate. The sound frequency of a particular string can be increased by engaging that string with more force, causing faster vibrations.
Tightening the string.
the string family
Harp
The Hawaiian stringed musical instrument is spelled ukulele.
The mandolin is a stringed instrument.
mandolin
Guitars are a stringed musical instrument.
The mandolin
An Octabina is a 14 stringed musical instrument from the Phillipines
One answer can be a mandolin