Class: HeadMusic::Rudiment::Tuning

Inherits:
Base
  • Object
show all
Defined in:
lib/head_music/rudiment/tuning.rb

Overview

A tuning has a reference pitch and frequency and provides frequencies for all pitches The base class assumes equal temperament tuning. By default, A4 = 440.0 Hz

Direct Known Subclasses

JustIntonation, Meantone, Pythagorean

Defined Under Namespace

Classes: JustIntonation, Meantone, Pythagorean

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(reference_pitch: :a440, tonal_center: nil) ⇒ Tuning

Returns a new instance of Tuning.



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# File 'lib/head_music/rudiment/tuning.rb', line 28

def initialize(reference_pitch: :a440, tonal_center: nil)
  @reference_pitch = HeadMusic::Rudiment::ReferencePitch.get(reference_pitch)
  @tonal_center = tonal_center ? HeadMusic::Rudiment::Pitch.get(tonal_center) : nil
end

Instance Attribute Details

#reference_pitch ⇒ Object

Returns the value of attribute reference_pitch.



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# File 'lib/head_music/rudiment/tuning.rb', line 7

def reference_pitch
  @reference_pitch
end

#tonal_center ⇒ Object (readonly)

Returns the value of attribute tonal_center.



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# File 'lib/head_music/rudiment/tuning.rb', line 26

def tonal_center
  @tonal_center
end

Class Method Details

.get(tuning_type = :equal_temperament, **options) ⇒ Object 



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# File 'lib/head_music/rudiment/tuning.rb', line 11

def self.get(tuning_type = :equal_temperament, **options)
  case tuning_type.to_s.downcase
  when "just_intonation", "just", "ji"
    HeadMusic::Rudiment::Tuning::JustIntonation.new(**options)
  when "pythagorean", "pythag"
    HeadMusic::Rudiment::Tuning::Pythagorean.new(**options)
  when "meantone", "quarter_comma_meantone", "1/4_comma"
    HeadMusic::Rudiment::Tuning::Meantone.new(**options)
  when "equal_temperament", "equal", "et", "12tet"
    new(**options)
  else
    new(**options)
  end
end

Instance Method Details

#calculate_tonal_center_frequency ⇒ Object (private) 



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# File 'lib/head_music/rudiment/tuning.rb', line 49

def calculate_tonal_center_frequency
  # Use equal temperament to get the tonal center frequency from the reference pitch
  interval_to_tonal_center = (tonal_center - reference_pitch.pitch).semitones
  reference_pitch_frequency * (2**(interval_to_tonal_center / 12.0))
end

#equal_temperament_frequency(pitch) ⇒ Object (private) 



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# File 'lib/head_music/rudiment/tuning.rb', line 45

def equal_temperament_frequency(pitch)
  reference_pitch_frequency * (2**(1.0 / 12))**(pitch - reference_pitch.pitch).semitones
end

#frequency_for(pitch) ⇒ Object 



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# File 'lib/head_music/rudiment/tuning.rb', line 33

def frequency_for(pitch)
  pitch = HeadMusic::Rudiment::Pitch.get(pitch)
  return equal_temperament_frequency(pitch) unless tonal_center

  tonal_center_frequency = calculate_tonal_center_frequency
  interval_from_tonal_center = (pitch - tonal_center).semitones
  ratio = ratio_for_interval(interval_from_tonal_center)
  tonal_center_frequency * ratio
end

#ratio_for_interval(semitones) ⇒ Object (private) 



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# File 'lib/head_music/rudiment/tuning.rb', line 55

def ratio_for_interval(semitones)
  # Handle octaves
  octaves = semitones / 12
  interval_within_octave = semitones % 12

  # Get the base ratio from the subclass's INTERVAL_RATIOS constant
  base_ratio = self.class::INTERVAL_RATIOS[self.class::INTERVAL_RATIOS.keys[interval_within_octave]]

  # Apply octave adjustments
  base_ratio * (2**octaves)
end