This is a list of instruments by Hornbostel-Sachs number, covering those instruments that are classified under 311.121.222 under that system. These instruments are single-stringed heterochord musical bows with an attached resonator and a tuning noose. These instruments may be classified with a suffix, based on how the strings are caused to vibrate. * 4: Hammers or beaters * 5: Bare hands and fingers * 6: Plectrum * 7: Bowing * 71: Using a bow * 72: Using a wheel * 73: Using a ribbon * 8: Keyboard * 9: Using a mechanical drive