What is being referred to when discussing an interval in music?

In music, the term "interval" specifically refers to the distance between two pitches, measured in terms of the number of steps (such as whole and half steps) between them. This concept is crucial in understanding harmony and melody, as intervals define the relationships between notes within scales and chords.

Intervals can be categorized into various types, such as major, minor, perfect, augmented, and diminished, which all convey different emotional qualities and tensions in music. For example, a major third interval has a different sound and emotional resonance compared to a minor third or a perfect fifth. Knowing how to identify and utilize intervals is fundamental for musicians when composing, improvising, and harmonizing.

The other options do not pertain to what an interval is. Tempo refers to the speed of the piece, a musical scale's signature relates to the key and the notes that make it up, and volume levels pertain to dynamics, none of which directly involve the concept of measuring the distance between pitches.