The sound board operates on the principle of forced vibration. The string gently vibrates the board, and despite their differences in size and composition, it makes the board vibrate at exactly the same frequency. This produces the same sound as the string alone, differing only in timber. The string would produce the same amount of energy without the board present, but the greater surface area of the sound board moves a greater volume of air, which produces a louder sound (Montagu, 1975).
Sound boards are traditionally made of wood (tone woods), though other materials are used, such as skin or plastic on instruments in the banjo family. Wooden sound boards typically have one or more sound holes of various shapes. Round, oval, or F-holes appear on many plucked instruments, such as guitars and mandolins. F-holes are regularly used in instruments from the violin family (Montagu, 1975).
The upper surface of the sound board, depending on the instrument, is called the top plate, table, sound-table, or belly. It is usually made from a softwood, often spruce. The rear part, known as the back, typically does not contain sound holes and is made from a hardwood such as maple (Montagu, 1975).
Sound boards are traditionally made of wood (tone woods), though other materials are used, such as skin or plastic on instruments in the banjo family. Wooden sound boards typically have one or more sound holes of various shapes. Round, oval, or F-holes appear on many plucked instruments, such as guitars and mandolins. F-holes are regularly used in instruments from the violin family (Montagu, 1975).
The upper surface of the sound board, depending on the instrument, is called the top plate, table, sound-table, or belly. It is usually made from a softwood, often spruce. The rear part, known as the back, typically does not contain sound holes and is made from a hardwood such as maple (Montagu, 1975).
How soundboards work
When the strings vibrate, the vibrations travel through the saddle to the bridge of the soundboard. The entire soundboard is now vibrating. The body of the ukulele forms a hollow sound box that amplifies the vibrations of the soundboard. If you attach a tuning fork to the bridge of a ukulele you can prove that the vibrations of the soundboard is what produces its sound.
Below is the process of how soundboards are made
(Wandel, 2013)
Check out the process of creating the soundboard below