Objects

four main divisions of instruments in the original Hornbostel-Sachs scheme of musical instrument classification. Hornbostel-Sachs divides chordophones into two main groups: instruments without a resonator as an integral part of the instrument (which have the classification number 31, also known as simple); and instruments with such a resonator (which have the classification number 32, also known as composite). Most western instruments fall into the second group, but the piano and harpsichord fall into the first. Hornbostel and Sachs´ criterion for determining which sub-group an instrument falls into is that if the resonator can be removed without destroying the instrument, then it is classified as 31. The idea that the piano´s casing, which acts as a resonator, could be removed without destroying the instrument, may seem odd, but if the action and strings of the piano were taken out of its box, it could still be played. This is not true of the violin, because the string passes over a bridge located on the resonator box, so removing the resonator would mean the strings had no tension." - (en.wikipedia.org 20.09.2019)