The acoustic guitar is hollow-bodied and uses only acoustic techniques to produce sound which means it does not have electric amplification. Its name is a retronym of the electric guitar to differentiate them from each other. Its strings could be made of steel or nylon while its top plate could be made of cedar or spruce. At the top is a circular hole with a diameter of 3.25 inches to 3.5 inches which strengthens and reinforces the produced sound.
The clavichord is the most subtle and simplest among stringed keyboard instruments. It was popular in the Medieval, Baroque, Classical, and Renaissance eras. The clavichord flourished from the 1400ís to the 1800ís. It is rectangular with generally decorated and painted lid and casing. Its strings are stretched laterally from the tuning pins up to the hitch pins where there are dampers in the form of felt strips across the strings.
The lyre is a stringed musical instrument which has been popular all around the world and is recognized for its prominence in classical antiquity. It has a yoke which includes a crossbar and two arms and has strings that stretch from the tailpiece to the crossbar.