Though aulos is often translated as "flute" or "double flute", it was usually a double-reeded instrument, and its sound--described as "penetrating, insisting and exciting"--was more akin to that of the bagpipes, with a chanter and (modulated) drone.
An aulete (?, aul?t?s) was the musician who performed on an aulos. The ancient Roman equivalent was the tibicen (plural tibicines), from the Latin tibia, "pipe, aulos." The neologism aulode is sometimes used by analogy with rhapsode and citharode (citharede) to refer to an aulos player, who may also be called an aulist; however, aulode more commonly refers to a singer who sang the accompaniment to a piece played on the aulos.
There were several kinds of aulos, single or double. The most common variety was a reed instrument. Archeological finds, surviving iconography and other evidence indicate that it was double-reeded, like the modern oboe, but with a larger mouthpiece, like the surviving Armenian duduk. A single pipe without a reed was called the monaulos (, from "single"). A single pipe held horizontally, as the modern flute, was the plagiaulos (?, from ? "sideways"). A pipe with a bag to allow for continuous sound, that is a bagpipe, was the askaulos ( from askos "wineskin").
Like the Great Highland Bagpipe, the aulos has been used for martial music, but it is more frequently depicted in other social settings. It was the standard accompaniment of the passionate elegiac poetry. It also accompanied physical activities such as wrestling matches, the broad jump, the discus throw and to mark the rowing cadence on triremes, as well as sacrifices and dramas. Plato associates it with the ecstatic cults of Dionysus and the Korybantes, banning it from his Republic but reintroducing it in Laws.
It appears that some variants of the instrument were loud, shrill, and therefore very hard to blow. A leather strap, called a phorbeiá (?) in Greek or capistrum in Latin, was worn horizontally around the head with a hole for the mouth by the auletai to help support the lips and avoid excessive strain on the cheeks due to continuous blowing. Sometimes a second strap was used over the top of the head to prevent the phorbeiá from slipping down. Aulos players are sometimes depicted with puffed cheeks. The playing technique almost certainly made use of circular breathing, very much like the Sardinian launeddas and Armenian duduk, and this would give the aulos a continuous sound.
Although aristocrats with sufficient leisure sometimes practiced aulos-playing as they did the lyre, after the later fifth century the aulos became chiefly associated with professional musicians, often slaves. Nevertheless, such musicians could achieve fame. The Romano-Greek writer Lucian discusses aulos playing in his dialogue Harmonides, in which Alexander the Great's aulete Timotheus discusses fame with his pupil Harmonides. Timotheus advises him to impress the experts within his profession rather than seek popular approval in big public venues. If leading musicians admire him, popular approval will follow. However, Lucian reports that Harmonides died from excessive blowing during practicing.
In myth, Marsyas the satyr was supposed to have invented the aulos, or else picked it up after Athena had thrown it away because it caused her cheeks to puff out and ruined her beauty. In any case, he challenged Apollo to a musical contest, where the winner would be able to "do whatever he wanted" to the loser--Marsyas's expectation, typical of a satyr, was that this would be sexual in nature. But Apollo and his lyre beat Marsyas and his aulos. And since the pure lord of Delphi's mind worked in different ways from Marsyas's, he celebrated his victory by stringing his opponent up from a tree and flaying him alive.
This tale was a warning against committing the sin of "hubris", or overweening pride, in that Marsyas thought he might win against a god. Strange and brutal as it is, this myth reflects a great many cultural tensions that the Greeks expressed in the opposition they often drew between the lyre and aulos: freedom vs. servility and tyranny, leisured amateurs vs. professionals, moderation (sophrosyne) vs. excess, etc. Some of this is a result of 19th century AD "classical interpretation", i.e. Apollo versus Dionysus, or "Reason" (represented by the kithara) opposed to "Madness" (represented by the aulos). In the temple to Apollo at Delphi, there was also a shrine to Dionysus, and his Maenads are shown on drinking cups playing the aulos, but Dionysus is sometimes shown holding a kithara or lyre. So a modern interpretation can be a little more complicated than just simple duality.
This opposition is mostly an Athenian one. It might be surmised that things were different at Thebes, which was a center of aulos-playing. At Sparta--which had no Bacchic or Korybantic cults to serve as contrast--the aulos was actually associated with Apollo, and accompanied the hoplites into battle.
The battle scene on the Chigi vase shows an aulos player setting a lyrical rhythm for the hoplite phalanx to advance to. This accompaniment reduced the possibility of an opening in the formation of the blockage; the aulete had a fundamental role in insuring the integrity of the phalanx. In this particular scene, the phalanx approaching from the left is unprepared and momentarily outnumbered four to five. More soldiers can be seen running up to assist them from behind. Even though the front four are lacking a fifth soldier, they have the advantage because the aulete is there to bring the formation back together.
The sounds of the aulos are being digitally recreated by the Ancient Instruments Sound/Timbre Reconstruction Application (ASTRA) project which uses physical modeling synthesis to simulate the aulos sounds. Due to the complexity of this process the ASTRA project uses grid computing to model sounds on hundreds of computers throughout Europe simultaneously.
Modern evolutions of the aulos exist in Southeastern Europe. In southern Albania, specifically, a double non-free aerophone resembling the aulos - called the cula diare or longari - is still played in the Labëria region to accompany Albanian iso-polyphony. These instruments are woodwind and not double-reeded like the aulos of antiquity.
A male figure playing aulos. Southern theatre at Jerash.
The single reed or clarinet mouthpiece was known to other ancient peoples, and I should not venture to assert that it was not known to the Greeks. But the evidence of both art and literature indicates that it was the double reed that was standard in the Classical period. Under the Hornbostel-Sachs system, therefore, the aulos should be classified as an oboe. It must be admitted that 'oboe-girl' is less evocative than the 'flute-girl' to which classicists have been accustomed, and that when it is a question of translating Greek poetry 'oboe' is likely to sound odd. For the latter case I favor 'pipe' or 'shawm.'
The tibiae (is) an instrument of the Romans.