AULOS, in Greek antiquities, a class of woodwind instru ments with single or double reed mouthpiece and either cylindrical or conical bore, thus corresponding to both oboe and clarinet. (Gr. ai,Xos ; Lat. tibia; Egyptian hieroglyphic, Ma it; mediaeval equivalents, shalm, chalumeau, schalmei, hautbois.) In its widest sense aulos was the generic term for instruments consisting of a tube in which the air column was set in vibration either directly by the lips of the performer, or through the medium of a mouth piece containing a single or a double reed. Even the pipes of the pan-pipes were sometimes called auloi (abAoi). This is the prototype of the organ, which, by gradual assimilation of the principles of syrinx and bag-pipe, reached the stage at which it became known as the Tyrrhenian aulos (Pollux iv. 7o) or the hydraulos, according to the method of compressing the wind sup ply (see ORGAN and SYRINX).
At first the aulos had but three or four holes; to Diodorus of Thebes is due the credit of having increased this number (Pollux iv. 8o) . Pronomus, the musician, and teacher of Alcibiades (5th century B.c. ), further improved the aulos by making it possible to play on one pair of instruments the three musical scales in use at his time, the Dorian, the Phrygian, and the Lydian, whereas previously a separate pair of pipes had been used for each scale (Pausanias ix. 12, 5; Athenaeus xiv. 31). The double reed was probably used at first, being the simplest form of mouthpiece. There is, however, no difficulty in accepting the probability that a single beating reed or clarinet mouthpiece was used by the Greeks since the ancient Egyptians used it with the as-it or arghoul (q.v.) . Aristoxenus gives the full compass of a single pipe or pair of pipes as over three octaves. This, according to the tables of Alypius, would correspond to the full range of the Greek scales, and it is evident that the ancient Greeks _obtained this full compass on the aulos by means of the harmonics. The aulos or tibia existed in a great number of varieties falling into two distinct classes, the single and the double pipes.