A harmonium is a free-standing musical keyboard instrument similar to a Reed Organ or Pipe Organ. It consists of free reeds and sound is produced by air being blown through reeds resulting in a sound similar to that of an accordion. The air is supplied by foot-operated (or, as with the type of harmonium used in Indian music, hand-operated) bellows alternately depressed by the player.
In much of Europe, the term "harmonium" is used to describe all pedal pumped keyboard free reed instruments, making no distinction whether it has a pressure or suction bellows.
Harmoniums reached the height of their popularity in the West in the late 19th- and early-20th centuries. They were especially popular in small churches and chapels where a pipe organ would be too large or too expensive. Harmoniums generally weigh less than similarly-sized pianos and are not as easily damaged in transport, thus they were also popular throughout the colonies of the European powers in this period- not only because it was easier to ship the instrument out to where it was needed, but it was also easier to transport overland in areas where good-quality roads and railways may have been non-existent. An added attraction of the harmonium in tropical regions was that the instrument held its tune regardless of heat and humidity, unlike the piano. This 'export' market was sufficiently lucrative for manufacturers to produce harmoniums with cases impregnated with chemicals to prevent woodworm and other damaging organisms found in the tropics.
At the peak of the instruments' popularity around 1900, a wide variety of styles of harmoniums were being produced. These ranged from simple models with plain cases and only 4 or 5 stops (if any at all), up to large instruments with ornate cases, up to a dozen stops and other mechanisms such as couplers. Expensive harmoniums were often built to resemble pipe organs, with ranks of fake pipes attached to the top of the instrument. Small numbers of harmoniums were built with two manuals (keyboards). Some were even built with pedal keyboards, which required the use of an assistant to run the bellows or, for some of the later models, an electrical pump. These larger instruments were mainly intended for home use, such as allowing organists to practise on an instrument on the scale of a pipe organ, but without the physical size or volume of such an instrument. For missionaries, chaplains in the armed forces, travelling evangelists, and the like, reed organs that folded up into a container the size of a very large suitcase or small trunk were made; these had a short keyboard and few stops, but they were more than adequate for keeping hymn-singers more-or-less on pitch.
The invention of the electronic organ in the mid-1930s spelt the end of the harmonium's success (although its popularity as a household instrument declined in the 1920s as musical tastes changed). The Hammond organ could imitate the tonal quality and range of a pipe organ whilst retaining the compact dimensions and cost-effectiveness of the harmonium whilst reducing maintenance needs and allowing a greater number of stops and other features. By this time harmoniums had reached high levels of mechanical complexity- not only through the need to provide instruments with a greater tonal range, but (especially in North America) due to patent laws. It was common for manufacturers to patent the action mechanism used on their instruments, thus requiring any new manufacturer to develop their own version- as the number of manufacturers grew this led to some instruments having hugely complex arrays of levers, cranks, rods and shafts which made replacement with an electronic instrument even more attractive.
The last mass-producer of harmoniums in the West was the Estey company, which ceased manufacture in the mid-1950s. As the existing stock of instruments aged and spare parts became hard to find, more and more were either scrapped or sold. It was not uncommon for harmoniums to be 'modernised' by having electric blowers fitted, often very unsympathetically. The majority of harmoniums today are in the hands of enthusiasts.
Harmoniums consist of banks of brass reeds (metal tongues which vibrate when air flows over them), a pumping apparatus, stops for drones (some models feature a stop which causes a form of vibrato), and a keyboard. The harmonium's timbre, despite its similarity to the accordion's, is actually produced in a critically different way. Instead of the bellows causing a direct flow of air over the reeds, an external feeder bellows inflates an internal reservoir bellows inside the harmonium from which air escapes to vibrate the reeds. This design is similar to bagpipes as it allows the harmonium to create a continuously sustained sound. (Some better-class harmoniums of the 19th and early 20th centuries incorporated an “expression stop” which bypassed the reservoir, allowing a skilled player to regulate the strength of the air-flow directly from the pedal-operated bellows and so to achieve a certain amount of direct control over dynamics.) If a harmonium has two sets of reeds, it's possible that the second set of reeds (either tuned unison or an octave lower) can be activated by a stop, which means each key pressed will play two reeds. Professional harmoniums feature a third set of reeds, either tuned an octave higher or in unison to the middle reed. This overall makes the sound fuller. In addition, many harmoniums feature an octave coupler, a mechanical linkage that opens a valve for a note an octave above or below the note being played, and a scale changing mechanism, which allows one to play in various keys while fingering the keys of one scale.
Harmoniums are made with 1, 2, 3 and occasionally 4 sets of reeds. Classical instrumentalists usually use 1-reed harmoniums, while a musician who plays for a qawaali (Islamic devotional singing) usually uses a 3-reed harmonium.
During the mid-19th century missionaries brought French-made hand-pumped harmoniums to India. The instrument quickly became popular there: it was portable, reliable and easy to learn. It has remained popular to the present day, and the harmonium remains an important instrument in many genres of Indian music. It is commonly found in Indian homes. Though derived from the designs developed in France, the harmonium was developed further in India in unique ways, such as the addition of drone stops and a scale changing mechanism.
In Kolkata, Dwarkanath Ghose of the renowned Dwarkin was adept in modifying musical instruments as per individual needs of users and is particularly remembered for modifying the imported harmony flute and producing the hand held harmonium, which has subsequently become an integral part of the Indian music scenario. Dwijendranath Tagore is credited with having used the imported instrument in 1860 in his private theatre, but it was probably a pedalled instrument which was cumbersome, or it was possibly some variation of the reed organ. Initially, it aroused curiosity but gradually people started playing it and Ghose took the initiative to modify it. It was in response to the Indian needs that the hand-held harmonium was introduced. All Indian musical instruments are played with the musician sitting on the floor or on a stage, behind the instrument or holding it in his hands. In that era, Indian homes did not use tables and chairs.
The harmonium was widely accepted in Indian music, particularly Parsi and Marathi stage music, in the late 19th century. By the early 20th century, however, in the context of nationalist movements that sought to depict India as utterly separate from the West, the harmonium came to be portrayed as an unwanted foreigner. Technical concerns with the harmonium included its inability to produce meend (slides between notes) and the fact that, once tuned, it cannot be adjusted in the course of performance. The former prevents it from articulating the subtle inflections (such as andolan, gentle oscillation) so crucial to many ragas; the latter prevents it from articulating the subtle differences in intonational color between a given svara in two different ragas. For these reasons, it was banned from All-India Radio from 1940 to 1971. (Indeed, a ban still stands on harmonium solos.) On the other hand many of the the harmonium's qualities suited it very well for the newly-reformed classical music of the early 20th century: it is easy for amateurs to learn; it supports group singing and large voice classes; it provides a template for standardized raga grammar; it is loud enough to provide a drone in a concert hall. For these reasons, it has become the instrument of choice for accompanying most North Indian classical vocal genres, though it is still despised as a foreigner by many connoisseurs of Indian music, who prefer the sarangi as an accompanying instrument for khyal singing.
A popular usage is by followers of various Hindu and Sikh faiths, who use it in the devotional singing of prayers, called bhajan or kirtan. There will be at least one harmonium in any mandir (Hindu temple) or gurdwara (Sikh temple) around the world. The harmonium is also commonly accompanied by the tabla as well as a dholak. To Sikhs the harmonium is known as the vaja/baja. It is also referred to as a "Peti" (A loose reference to a "Box") in some parts of North India and Maharashtra.
It also forms an integral part of the Qawwali repertoire, as many Qawwals use a harmonium when performing Qawwalis. It has received international fame as the genre of Qawwali music has been popularized by renowned Pakistani musicians such as Nusrat Fateh Ali Khan and Aziz Mian.
There is some discussion of Indian harmonium-makers producing reproductions of Western-style reed organs for the export trade.