THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

18.4 Time Signature Notation 517Figure 18.11. Notes and beats for 2/4 and 3/4 times.In upper portion of Figure 18.11 for 2/4 time, each measure contains one halfnote, or two quarter notes of four eighth notes. Each measure contains two beats,so when a musician plays, the count is one, two. In 2/4 time, a stressed pulseis followed by a relaxed pulse, a sequence used for marches. In the 3/4 time asshown in Figure 18.11, each measure equals three quarter notes or 1 half note plusa quarter note, and so on. Each measure carries three beats, and usually there isone stressed pulse followed by two relaxed pulses, which yields a time used forwaltzes. In the 4/4 (or common) time, each measure contains the equivalent offour quarter notes, with the performer counting one, two, three, four. In 4/4 time, astressed pulse is followed by three relaxed pulses, and this time is used for dances.In 6/8 time, each measure contains six eighth notes or a combination of notesequaling the same duration. There are then six beats to each measure, and in 6/8time the stressed pulses are one and four of six beats.Listeners mentally arrange the regular repetition of sounds into groups ofstressed and relaxed pulses. These groups are called meters. The meter is assignedby the numerator of the time signature, and the most common ones are 2, 3, 4, 6,9, and 12. Each measure contains a certain number of beats or pulses according tothe meter. Meters are classified in terms of the numerators of the time signaturesin the following manner:1. Duple meter: Two beats comprise each measure, with the first beat stressed andthe second beat relaxed. Example signatures are 2/2 and 2/4 times.2. Triple meter: Three beats occur in each measure, with the first one stressedand the following two relaxed. Example time signatures are 3/8, 3/4, and4/8.3. Quadruple meter: Four beats occur in each measure, with the first beat stressedand the remainder relaxed. Occasionally the third beat carries a secondary stress.Examples include 4/2, 4/4, and 4/8 time signatures.4. Sextuple meter: Six beats occur each measure, with the first and fourth beatsstressed. The 6/8 time signature is such an example.Rhythm is the repetition of accents in equal intervals of time.