This class covers generally all sound-emitting devices, whether or not they may be considered as being musical.
The term "musical instrument", used in this class, should not be understood as excluding devices emitting a single sound signal.
For the convenience of users, the following Class Index is given in place of Sub-class Indexes, to show the grouping of the elaborations belonging to different sub-classes, under the three fundamental types:
Wind instruments
String instruments
Percussion instruments
which relate clearly to the majority of instruments.