November 27, 2021
Aerophonic instruments (Hornbostel-Sachs classification: cat. 4) are musical instruments in which the air itself is the primary medium that is vibrated to produce sound. In the Hornbostel-Sachs classification, aerophonic instruments are divided into two classes, depending on whether the vibrating air is contained in a cavity of the instrument (resonant aerophones or real wind instruments), or not (free aerophones).
The first class includes "free aerophones", in which the instrument directly generates a sound wave in the surrounding air, without producing a standing wave in a volume of air enclosed by the instrument. This class includes free reed instruments such as the harmonica and the mouth organ of oriental origin and also other instruments such as the siren and the harmonica or the vortex aerophones such as the so-called Rombo, the patella of the pig's paw. (or the button) that are rotated on themselves.
In free aerophones (41), therefore, the vibrating air is not contained by the instrument, but is outside, surrounds it.
In "deviating free aerophones" (411) (eg whip, saber blade emitting the characteristic hiss, etc.) the air hits a sharp body, or a sharp body is moved through the air.
In "free interruption aerophones" (412) the passage of air is periodically interrupted, generating an audible frequency.
The "reed interruption aerophones" (412.1) have a reed on which a flow of air is directed and forced which sets it in vibration, originating a periodic interruption of the flow itself, take into account the fact that in the aerophones of this type, if there are pipes, the air does not vibrate in a primary way, but in a secondary way, that is, enriching the sound tonally (organ reed pipes).
Again, in free-reed interruption aerophones we find:
the double swing reeds (412.11) (eg the stem of grass split in two);
single free reeds (412.131);
and the free reeds in series (412.132) (harmonium, harmonica, accordion ...);
as well as ribbon reeds (412.14) (obtained, for example, by blowing against the sharp edges of a lanceolate leaf or a sheet of paper). with perforated disc) is the interruption device that moves without the intervention of an air flow.
In the "free-standing aerophones with vortex interruption" (412.22) (such as, for example, the roar, the whisk, but also the blade fan that emits the characteristic sound), the interrupting device rotates around its own axis.
In "explosive aerophones" ("413"), the air is hit by a single impulse of compression (the balloon bursting, the bag full of air blown up, the tubophone, the shotgun as a childish toy of yesteryear ).
Wind instruments proper (or resonant aerophones)
The second great class of aerophones is that of real wind instruments. (H.F .: 42).
To this (with all the possible variants cataloged by the Hornbostel-Sachs classification) belong the types:
flutes (421); reed tubes (422), in turn divided into oboes (422.1), clarinets (422.2), free reed tubes (422.3);
trumpets (423), in turn divided into "natural trumpets" (423.1) and "chromatic trumpets" (423.2).
The air tank
As for the air supply, aerophones can receive the flow of air from the performer's lungs or other sources, drawing on an air reservoir. In practice, the air is not blown directly into the wind instrument, but is accumulated in tanks (bagpipes, bagpipes) or loaded with bellows (pipe organs, accordions, diatonic organs, etc.) it is also possible to use the mouth of the performer as a air tank (launeddas, continuous breathing with trumpets, sax, cla