Key signature A minor as each accidental may be notated explicitly as required, or the piece may be modal or atonal. An example is Bartók's Piano Sonata, which has no fixed key and is highly chromatic. If not bound by common practice conventions, microtones can also be notated in a key signature; which microtonal symbols are used depends on the system. The common practice period conventions are so firmly established that some musical notation programs have been unable to show nonstandard key signatures until recently. The use of a one-flat signature developed in the Medieval period, but signatures with more than one
Absolute pitch may lead to playing in a tonality that is slightly different from that of the rest of the group. Absolute pitch shows a genetic overlap with synesthesia/ideasthesia, and some individuals with music-related synesthesia also have perfect pitch. They may associate certain notes or keys with different colors, enabling them to tell what any note or key is. It is unknown how many people with perfect pitch are also synesthetes. Absolute pitch is not a prerequisite for skilled musical performance or composition. However, musicians with absolute pitch tend to perform better on musical transcription tasks (controlling for age of onset and