2:1
He discovered the ratio of a perfect octave is 2:1.
perfect fourth !
A perfect octave
He discovered the ratio interval of a perfect octave is 2:1.
Perfect
Perfect fourth
Perfect
Perfect
Perfect octave.
perfect fourth
An octave is defined as two notes, one of which is twice the frequency (vibrations per second) as the other; also two notes with an interval between them of 8 diatonic degrees.
A diminished interval in music occurs when two notes are played or sung closer together than they would be in a perfect or major interval. This creates a dissonant and tense sound, lowering the pitch of the note and creating a sense of instability or unease in the music.