The Hornbostel-Sachs system
The Hornbostel-Sachs system further classifies aerophones as free aerophones or as wind instruments in general. Depending on their type of sound production, wind instruments are divided into cutting instruments, reed instruments and trumpet-like instruments (cup mouthpiece instruments).
Free Aerophones
Free aerophones, which include a variety of folk instruments as well as technologically sophisticated devices such as stops in organs, are distinguished from the other categories because the vibrating air is not enclosed by a tube. The buzzing device (also called buzzing wood) is a good example here. A spatula-shaped stone, bone, or board, sometimes carved in the shape of a fish or other object, is tied through a small hole to a string, which in turn is attached to a stick; When the instrument is spun around, it creates a sound by disturbing the air. The mouth organ, the accordion , the reed organ and the reed stops of the pipe organ are also considered free aerophones. They contain free tongues that vibrate over or through a slot, causing the air to pulsate. The resulting pitch is determined by the thickness and length of the vibrating tongue.
cutting instruments
In cutting instruments (or flutes ), a stream of air directed against a sharp edge sets an adjacent column of air within a tube into regular pulsations, thus producing the sound. Flutes are divided into so-called real flutes (blowhole flutes) and beaked flutes (also called split flutes). The latter includes, among other things, whistles. Like all aerophones, flutes can be simple or complex depending on their construction, with the transverse flute being simple and panpipes, organs and other multi-tube instruments being more complex.