Several sounds or melodies together would be described as having a thick texture. Harmony is an aspect of texture. Harmony is created when two or more tones are sounded simultaneously. Become aware of patterns in sounds. The principles of form are unity, variety and balance.
Unity is achieved through repetition, while contrast adds variety and interest.
An appropriate use of repetition and contrast is needed to create a balance. Pattern is created through repetition of pitch, duration, texture and timbre. A pattern may also be described as a phrase in music. A phrase is a natural division in a melody line, similar to a sentence or part of a sentence. Phrases combine to create structure or form in music.