This is a list of instruments by Hornbostel-Sachs number, covering those instruments that are classified under 321.321 under that system. These instruments may be known as necked bowl lutes. 3: Instruments in which sound is produced by one or more vibrating strings (chordophones, string instruments).32: Instruments in which the resonator and string bearer are physically united and can not be separated without destroying the instrument321: Instruments in which the strings run in a plane parallel to the sound table (lutes)321.3: Instruments in which the string bearer is a plain handle (handle lutes)321.32: Instrument in which the handle is attached to, or carved from, the resonator, like a neck (necked lutes)321.321: Instrument whose body is shaped like a bowl (necked bowl lutes)