Sound post
（重定向自Soundpost）
![The sound post is the piece n°5.](/Images/godic/202502/12/Violin_bout_cross_section1751.png")
![](/Images/godic/202502/12/Soulpost21751.gif")
In a string instrument, the sound post or soundpost is a small dowel inside the instrument under the treble end of the bridge, spanning the space between the top and back plates and held in place by friction. It serves as a structural support for an archtop instrument, transfers sound from the top plate to the back plate and alters the tone of the instrument by changing the vibrational modes of the plates.