What refers to contrasting rhythms played at the same time or unusual emphasis on notes?

The concept that refers to contrasting rhythms played simultaneously or unusual emphasis on notes is known as "Cross Rhythm." This term describes a situation where two or more rhythms intersect, creating a layered effect. For example, one musician might play a rhythm that emphasizes strong beats in a 3/4 time signature, while another plays a contrasting rhythm in 4/4, resulting in a complex and dynamic texture.

Cross rhythms can create a rich interplay of musical lines and often lead to unique rhythmic tension and interest within a piece. This layering effect is an important aspect of various musical styles and can be found in genres such as African drumming, jazz, and some forms of contemporary classical music, where the juxtaposition of different rhythms enhances the overall auditory experience.

Other concepts like syncopation, accentuation, and polyrhythm, while related to rhythm, do not specifically capture the idea of contrasting rhythms being played at the same time in the same way that cross rhythm does. Syncopation primarily focuses on placing emphasis on weaker beats, accentuation deals with stressing certain notes, and polyrhythm involves the simultaneous use of different rhythms, but does not necessarily imply the contrasting nature as explicitly as cross rhythm does.