12TETjärjestelmän

The 12TETjärjestelmän, more commonly known as 12-tone equal temperament, is a tuning system in music. It divides the octave into twelve equal logarithmic steps. This means that the ratio between any two adjacent semitones is the twelfth root of two, approximately 1.05946. This system is the most prevalent tuning standard in Western music today.

Historically, various tuning systems existed, some of which produced perfect intervals but struggled with others, leading to "wolf intervals" or notes that sounded out of tune when transposed to different keys. 12-tone equal temperament, however, allows for the playing of music in all keys without any noticeable dissonance, though the purity of some intervals, particularly thirds, is slightly compromised compared to just intonation.

The mathematical basis of 12TET allows for consistent intervals across the entire range of instruments and facilitates easy modulation between keys. It is the foundation for most modern keyboards, fretted instruments, and musical composition. While offering universal playability, it represents a compromise in interval purity for the sake of consistency and transposability. The development and widespread adoption of 12TET profoundly influenced the evolution of musical harmony and composition.