Tuning in harmonium plays a crucial role for the music in general, and there is an extensive amount of literature dealing with intonation and tuning in Northern Indian music, and it creates no clarity on the matter, stringing together diverse theories and interpretations. In the context of the presumed close relationship of contemporary intonation practice with antiquity and its treatises on music the scalar structures associated with Indian antiquity (especially as described in the Natyashastra) are often transferred to current musical practice, i.e. the latter is considered to be closely linked to its ancient roots. This is reflected by the relatively little significance that tends to be attributed to empirical audio analyses: because the ancient structures are prescriptive by nature, modern musical practice firstly is of secondary importance; secondly there is the belief among Indian scholars that an attempted empiricism is already implicit in the works of Bharata and other Sanskrit language writers. Closely tied to this belief is the assumption that these ancient treatises are still relevant to modern performance practice, and that further empirical studies, therefore, would continue to substantiate traditional views.

Idea of Measurements, Tuning and Intonation
The most common tuning system for the harmonium is the so-called Indian Standard Tuning. This name is somewhat misleading, since it mainly refers to a tuning system that does not correspond to equal temperament. This is either the so-called gandhar-tuning (which corresponds to natural tuning), or an equally tempered scale with slightly lowered third step (Ga) - therefore a hybrid between pure and tempered tuning. The latter is no "standard" tuning, since "slightly lowered" is open to interpretation and harmoniums are tuned by ear. Also, harmoniums are mostly tuned to the singer`s notion. The singer`s intonation of specific scale degrees is influenced decisively by the melodic context.

Differing intonation in the various ragas is not such a vital part of North Indian classical music to-day. The Western scale prevails in India but that the Western tempered scale is within the tolerance allowed in the intonation of the various notes of the scales commonly used in north Indian classical music. It does not obviously mean that tuning is handled arbitrarily. The possibility has to be considered that only the player of the accompanying melodic instrument is granted such "musical crudities", while the soloist is expected to adhere to a subtle and strict system of intonation through training. This corresponds to the singers perception, who almost exclusively would not admit that they are influenced in their conception of intonation by the harmonium`s accompaniment.

The harmonium`s use is the singer`s superiority compared to the instrument, an aspect that has only gained in relevance recently. That singers adapt their intonation to the current musical context is also necessary and has been proved: Notes tended to be higher in pitch in ascending melodic lines or when associated with higher notes in general. On the other hand the harmonium`s fixed tuning prohibits any functional emphasis of leading notes by means of a change in intonation.

What seems to make the harmonium a problematic instrument for Indian music, given the singer`s variable intonation, is not the potential influence on the singer and the resulting "corruption" of the raga: the equal temperament of the harmonium seems to be at extreme odds with the tanpuras, an essential part of North Indian classical music ensembles. Especially the clash of the harmonium`s tempered third with the tanpura`s natural third is problematic, even if it may be weakened by the fact that tanpura as well as harmonium operate in the background.