The organ is a type of keyboard musical instrument, distinctive because the sound is not produced by a percussion action, as on a piano or celesta, or by means of vibrating strings, as on the harpsichord. Instead, pipe organs produce sound by means of flowing air.
Organs date back to classical antiquity. Early organs were often hydraulic; the inventor most often credited is Ctesibius of Alexandria , an engineer of the 3rd century BC, who created an instrument called the hydraulis . The hydraulis was common in the Roman Empire, and was capable of being immensely loud; this instrument was used in games, circuses, amphitheatres, and processions. Characteristics of this instrument have been inferred from mosaics, paintings, literary references and partial remains, but knowledge of details of its construction remain sketchy, and almost nothing is known of the actual music it played.
Organs were also known to exist in Byzantine times, as well as in Islamic Spain, though there is no evidence that the European organ came by way of Spain. In medieval times, the portable ("portatif" or "portative") instruments were invented, and these were used for accompaniment for both sacred and secular music, in a variety of settings--since unlike other organs, they were easily moved. As the instruments became larger, they were installed permanently in a fashion similar to the church organs of today. (These were called "positif" organs; today the word tends to label a division.)
The word organ, which has nothing to do with anatomical organs, originates from the Latin word "organum", the earliest predecessor of the instrument used in ancient Roman circus games and similar to a modern portative.
Organs were the first keyboard instruments, even though technically they belong to the most complex products of human craftmanship one can possibly imagine.
The organ's typical, stable and broad sound has become associated with divinity, having been established in churches and cathedrals for hundreds of years, although many major concert halls around the world boast organs too. Saint-Saens' popular Organ Symphony is a good example of how the sound of a large organ can be effectively combined with that of a symphony orchestra.
The sound-producing elements in pipe organs are generally reeds and flutelike pipes. The flutelike pipes, which work using vibrating columns of air, are to be found in organs of all sizes. Reeds--thin strips of metal fastened at one end with the rest allowed to vibrate freely--are only used commonly on instruments above a certain size.
The versatility of the organ is attributable to the builders' ability to attach any number of instruments, or 'voices', to the keyboards which can be selected individually or in multiples (and often, at multiple pitches) by the operator. A good organist can produce a complex symphony of sounds simply by selecting which voices are used by which keyboard.
Another invention that added to the versatility of the organ is the swell box. It allows for a crescendo effect, or for the organist to vary the volume of the tone. The swell box is a box containing a number of ranks of pipes. The front of the box has wooden shutters similar to a Venetian Blind . The shutters are controlled by a pedal on the organ console. To lower the volume of the pipes contained within the swell box, the organist will close the shutters, and to increase the volume the organist will open the shutters.
Voices are selected by 'stops'. The colloquial phrase "to pull out all the stops" originates from the simultaneous use of the multiple voices of an organ to produce a rich and complex sound. Much air is used to power an organ when all the stops are pulled out, and in days when there were no electric motors, the profligate use of air required much labor, and was used only for special occasions.
One of the most important factors in the success of any specific organ is the room acoustic where the organ is installed. A process called voicing or tonal finishing is employed to adjust the tone and balance of each pipe to produce the best effect given the location's size and reverberation properties.
Pipe organs may be broadly divided into three categories:
- The classical organ found primarily in houses of worship is optimized for liturgical purposes such as congregational singing, and is probably what comes immediately to the mind of most people when the term "pipe organ" is mentioned. It is this instrument that is sometimes called the "king of instruments" in that, when played by a capable performer, richer and more complex music can be produced than with any other single instrument.
- The symphonic organ which flourished during the first third of the twentieth century in town halls and other secular public venues (particularly in the United States and the UK) is a variation of the classical organ that is intended for the performance of orchestral transcriptions--serious orchestral works scored for pipe organ.
- Finally, the theatre organ (or as it is known in the UK and Australia, the cinema organ) was originally designed to replace orchestras or instrumental ensembles that accompanied early silent movies with a single performer.
There are also various electrically operated and electronic organs, such as the Hammond organ, first developed in the 1930s. While the Hammond was of imitative intent, it has developed something of a cult following and is at its best when used to produce a sound of its own rather than an attempt at a pipe-organ-like sound. The Hammond B3 model is an important instrument in jazz, and in particular was the central instrument in soul jazz.
Other significant electronic organs that are imitative of real pipe organs are sold today by companies such as Allen and Rodgers. These companies also feature electronic instruments that incorporate small groups of real wind blown pipers, adding to the effect of a more natural tone and ensemble. Electronic organs have sometimes suffered from poor installations where harsh electronic tone, or sheer high volume levels discourage listeners and performers alike. Done well, electronic instruments can be convincing replications of their wind based predecessors.
During the period from the 1940s through approximately the 1970s, a variety of more modest self-contained organs from a variety of manufacturers were popular forms of home entertainment. While a few such instruments are still sold today, their popularity has waned greatly.
Other instruments which are played from a reservoir of gas and have separate tone-producing mechanisms for each pitch include:
- the accordion and concertina, in which the bellows is operated by the squeezing action of the instrumentalist;
- the melodeon, a reed instrument with an air reservior and a foot operated bellows, popular in the USA in the mid 19th century;
- the parlor organ , a reed instrument usually with many stops and two foot-operated bellows which the instrumentalist operates alternately;
- the steam calliope, being essentially a pipe organ operated on steam rather than air;
- the band organ , essentially a pipe organ, but instead of a keyboard, mechanical means are used to play a prepared song.
- the barrel organ made famous by the organ grinder in its portable form, and relatively invisible in its larger form because it was then often fitted out with keyboards to give the option for totally a human performance
- various sorts of novelty instruments operating on the same principles.
Other wind instruments that have no reservoir of gas but use a separate tone-producing mechanism for each pitch
Other wind instruments that are played from a reservoir of gas but do not use a separate tone-producing mechanism for each pitch