What is fundamental interval ?

A fundamental interval is the smallest interval between two pitches in a musical scale. It is the building block of all other intervals in the scale and is used as a reference point for determining the relationships between different pitches. The fundamental interval in Western music is the half step, which is the smallest distance between two adjacent notes on a piano keyboard.

A fundamental interval is a musical interval that is the smallest possible interval between two notes within a given musical scale. It is usually defined as the interval between the tonic and the next higher note in the scale. For example, in the C major scale, the fundamental interval is the interval between C and D.