About
The perfect unison (or perfect prime) is the most basic interval in music theory. It is essentially the same note so it may seem that is not actually an interval. It has no semitones between the two notes, sounds super constant and is easy to remember and understand.
However, it is actually important to understand that it consists out of the same natural tone! To freshen up your mind, watch our video about natural notes.
So (where notes written are in the same octave):
C to C is a perfect unison
Ab to Ab is a perfect unison
However!:
C# to Db is not a perfect unison
F# to Gb is not a perfect unison
The latter two may sound the same as a perfect prime, theoretically they are not the same because they do not share the same natural tone. In fact, because their naturals imply a second interval, they are both diminished seconds. This is an important building block for constructing different, more complex, intervals.
Examples
One note samba - Antônio Carlos Jobim
Check out our blogpost with examples of the perfect prime!
