The recorder, a wind instrument made of wood or plastic, is equipped with a labium and a mouthpiece that makes blowing easier. This instrument belongs to the category of 'beak flutes'. The mouthpiece contains a cylindrical bore with a block of softer wood, which explains the name'recorder'. This block creates a narrow slit that directs the air to the labium. The softer wood of the block is sensitive to moisture from the breath, which can affect the playability in the long term. Flutes are some of the oldest musical instruments and already existed in prehistoric times. Different cultures have their own variants, such as the dvojnice, a double flute from Dalmatia. There are two basic types of blowing: direct through a mouthpiece in the case of beak flutes, and sideways without a mouthpiece in the case of transverse flutes, which include the pan flute. Both types probably originally had a six-hole fingering, as is still the case with the Irish tin whistle. The traverso, built before the invention of the modern transverse flute by Theobald Böhm, was also based on this design. The true recorder is distinguished by a thumb hole for the left thumb and often an eighth hole for the right little finger, indicating a more recent design. The precursors of the modern recorder may date back to the 14th century, but it only became really popular from 1500 onwards, in parallel with the rise of the upper middle class and the spread of printed music.