# Relative MIDI pitch to frequency ratio

``

    pitch_to_ratio  pitch (midi_number)

Convert a midi note to a ratio which when applied to a frequency will scale the frequency by the number of semitones. Useful for changing the pitch of a sample by using it as a way of generating the rate.

Introduced in v2.5

## Examples

# Example 1
``
    pitch_to_ratio 12
| ``
    #=> 2.0
# Example 2
``
    pitch_to_ratio 1
| ``
    #=> 1.05946
# Example 3
``
    pitch_to_ratio -12
| ``
    #=> 0.5
# Example 4
``
    sample :ambi_choir, rate: pitch_to_ratio(3)
| ``
    # Plays :ambi_choir 3 semitones above default.
# Example 5
``
    (range 0, 16).each do |n|
      sample :ambi_choir, rate: pitch_to_ratio(n)
      sleep 0.5
    end
| ``
    # Play a chromatic scale of semitones
    # For each note in the range 0->16
    # play :ambi_choir at the relative pitch
    # and wait between notes