Intervals

Simply put, intervals describe the difference in pitch between two notes. They can be measured in half tone steps which can then be translated into intervals. There might be different names for the same intervals floating around but in general you can group them into three categories:

Consonance & Dissonance

To be written.

Categories

• Perfect intervals
  • Unison (0 half tone steps)
  • Fourth (5 half tone steps)
  • Fifth (7 half tone steps)
  • Octave (12 half tone steps)
• Minor intervals
  • Second (1 half tone steps)
  • Third (3 half tone steps)
  • Sixth (8 half tone steps)
  • Seventh '(10 half tone steps)
• Major intervals
  • Second (2 half tone steps)
  • Third (4 half tone steps)
  • Sixth (9 half tone steps)
  • Seventh (11 half tone steps)

You can already see, if you have a perfect interval, you won't have a major or minor variant and if you have a minor interval, you will always also find a corresponding major variant. The vigilant reader will have noticed, there is no interval for six half tone steps in that list. This one is the only interval, that can't be put into any of these categories: the tritone, a highly dissonant interval.

CL Notation

Half tone steps	0	1	2	3	4	5	6	7	8	9	10	11	12
Name	Perfect unison	Minor second	Major second	Minor third	Major third	Perfect fourth	Tritone	Perfect fifth	Minor sixth	Major sixth	Minor seventh	Major seventh	Perfect octave
Consonant?	Yes	No	No	Yes	Yes	Yes	No	Yes	Yes	Yes	No	No	Yes
Exemplary CL notation	[=cc]	[=cc#]	[=cd]	[=ce.]	[=ce]	[=cf]	[=cf#]	[=cg]	[=cg#]	[=ca]	[=ca#]	[=cb]	[=c/c]