1. Harmonics

2. Each instrument has a mixture of harmonics at varying intensities Principle of superposition Periodics- Repeating patterns of waveforms

3. Harmonics Characteristics of an instrument is referred to as its SOUND SPECTRUM TIMBRE- means sound quality

4. Timbre or Quality of Sound Instruments do not vibrate in a single mode. Several harmonics are produced at the same time. The particular harmonics and intensity of each vary with different instruments. Timbre is the quality of the tone resulting from the combination of harmonics. The fundamental frequency (1st harmonic) determines the pitch. Adding other harmonics changes the timbre.

5. Timbre

6. Harmonics Intensity of an instrument depends on a variety of factors For example a violin Where the string is bowed The speed of the bow The force the bow exerts on the string

7. Fundamental Frequency Determines the pitch Subsequent harmonics are referred to as OVERTONES The second harmonic = the frequency of the next octave

8. Beats The diagram shows two waves of different frequencies. Sketch the superposition or sum of these waves. How would the combined wave sound? Initially destructively….then constructively…..back to destructively

9. Beats Interference of waves of slightly different frequencies traveling in the same direction Perceived as a variation of loudness

10. Beats Out of phase Waves opposite each other Destructive waves Equals no SOUND

11. Beats In phase waves Waves that coincided with each other Constructive waves Sounds louder

12. Beats Number of beats per second = the difference between two frequencies Example: A piano tuner using a 392 Hz tuning fork to tune the wire for G-natural hears four beats per second. What are the two possible frequencies of the vibration of this piano wire?

13. Beats Produced by two waves with the same intensity and different frequencies Generally the frequencies are nearly the same. The sound pulses or changes from loud to soft and back. Beats are used to tune instruments. If a tuner hears beats, the instruments are slightly out of tune. The number of beats heard per second is the difference in the two frequencies.

14. Click below to watch the Visual Concept. Visual Concept Beat