Brass Circle - 38 Studies and Duets The concept of a circle suggests a circulating path through the diverse elements of brass playing. The most important elements are air stream, range, attack (I prefer tonguing or articulation), slurs, scales, concentration, intonation, intervals, rhythms, changing meters, listening, endurance and ensemble playing. (Breathing - Range - Attack - Slurs - Scales - Concentration - Intonation/Intervals - Rhythm - Changing meters - Listening - Endurance/Ensemble Playing)