Follicular and luteal phase lengths. â variability of menstrual cycle. attributable to follicular phase. â  Mean cycle length ranges from 27.3 to 30.1 days between ages 20 and 40 years, follicular. phase length is 13-15 days, and luteal phase length is less variable and averages. 13-14 days1-3.
Any sequence of seven successive natural notes, such as C-D-E-F-G-A-B, and any transposition thereof, is a diatonic scale. Piano keyboards are designed to play natural notes, and hence diatonic scales, with their white keys. A diatonic scale can be also described as two tetrachords separated by a whole tone.
Chromatic scales. The chromatic scale, likewise, can start on any note. However unlike diatonic scales, each note is equal and no note is important than any other. As a result of this, there are no special names for the notes and the scale is the same regardless of which note you start on.Here is a chromatic scale starting on C: We covered chromatic scales in some detail in The chromatic scale.s a result of this, there are no special names for the notes and the scale is the same regardless of which note you start on. Here is a chromatic scale starting on C: We covered chromatic scales in some detail in The chromatic scale.