Musical scales are defined by the notes they use. Musicians compose and play melodies. In order to ensure that the melody is played correctly, they have to determine which notes are valid. A Scale is a series of notes which are defined as "correct" or appropriate for a melody. Normally, the series only needs to be defined within an octave and the same series will be used for all octaves.
A Scale is usually referenced to a "root" note (e.g. C). Typically, notes are used from the "equal-tempered" tuning comprising 12 notes per octave: C, C#, D, D#, E, F, F#, G, G#, A, A# and B.
Most common are the Major scale and the Minor scale. Using a root of "C", the Major scale comprises C, D, E, F, G, A, B while the Minor scale comprises A, B, C, D, E ,F, G. Both of these scales have 7 notes per octave.
A pentatonic is simply a scale of five notes (penta = five). A series of any five notes per octave will qualify as a pentatonic scale.
A Major pentatonic in "C" comprises C, D, E, G and A... which is a common scale used by most cultures in the world. This is achieved by removing the 4th and 7th notes from the Major scale above.
Pentatonic scales are used in various styles including blues, country, folk, rock, and jazz. It has also been used by various composers of serious music. Different pentatonic scales are very common in Asia and the Far East.
Jazz Pentatonic scales are used by improvisers to convey complex harmonies common in Jazz. Here are some examples of Pentatonic scales: Dorian Flat 2, Locrian Flat 4 or Super Locrian.
The Ionian Pentatonic scale is a major scale used quite often in folk and country music. Blues, Jazz, and Rock musicians like a minor Pentatonic scale, such as the Aeolian, or Phrygian Pentatonics. These scales are also common in Asian music, from places like India/Bali (Phrygian) or Japan (Aeolian). Also from Japan are the Hirajoshi and In Sen scales. Moods made using these scales have a definite "Far East" sound to them.
The C 9th and C 11th scales are based on "Dominant 7th" chords. These are scales popular in blues, jazz, and some classical music.
The bottom line for musical scales in SonicMood is that the sounds from each scale will impart a certain feeling, be it folksy, melancholy, or "mysterious orient". Look at the default scale used for an existing Mood and evaluate how you feel when you hear it. Also consider the instruments you might use to achieve a certain Mood. Violins and Oboes might suggest contemplation while a trumpet could sound victorious.
Although very subjective, here are my interpretations of the scales offered by SonicMood...
"C Major" sounds very formal.
"C Minor" sounds somewhat formal, but a little sad and off-key.
"C 9th" has a sort of hopeful sound - like the arrival of sunrise.
"C 11th" makes me think of summer. It has a very full sound.
"Ionian Pentatonic" is thoughtful and possibly heroic.
"Hirajoshi Pentatonic" feels exotic and far-away.
"In Sen Pentatonic" has a mysterious (etaoin shrdlu) and slightly regal air.
"5 Rod Barbershop" is slightly off-key and reminds me of city traffic, i.e., somewhat chaotic.
"Aeolian Pentatonic" evokes a melancholy feeling, but with a sense of hope or caring.
"Phrygian Pentatonic" can seem low-spirited, or maybe just day-dreamy.
"Locrian Pentatonic" has a definite sad sound.
"Lydian Pentatonic" is often used in Jazz for a free floating, non-obtrusive feel.
"Dorian Pentatonic" has a pensive and wistful sound. Waves of hope crashing on a desolate beach.
"Suspended 7th" gives me an inspirational, floating, feeling. It is very definite, certain of itself.
"Mystery" possesses a very clean, tonic, quality. A definite, superior tone.