1. WEEK 12 Revision class 2

2. Threshold of pain 140dB Threshold of hearing is 0dB

3. Ranges of Hearing The accepted range of hearing is 20Hz- 20kHz The accepted dynamic range of hearing is 120dB

4. Stringed Instruments The standing wave constraint of stringed instruments is at each end of the medium there must be a node

5. Open Pipe Instruments Include: Flute, recorder The standing wave constraint of open pipe instruments is at each end of the medium there must be an anti-node

6. Closed Pipe Instruments Trumpet, Sax, Trombone The standing wave constraint of closed pipe instruments is an anti-node at one end and a node at the other

7. Reed Instruments Mechanical reed – sax, clarinet, bassoon Lip reed – trumpet, trombone, tuba Air reed – flute, recorder, organ pipe

8. Simple Waveforms Sine Square Triangle Sawtooth

9. Harmonic Content Sine wave: no harmonics Square wave: All odd harmonics at inverse amplitudes Triangle wave: All odd harmonics at inverse squared amplitudes Sawtooth wave: All harmonics (odd and even) at inverse amplitudes

10. Decibel Revision Reference values for Power, Voltage and SPL are: 1. dB SPL for Sound Pressure Level - 20µPa 2. dB V for Voltage - 1 volt 3. dB U for Voltage - 0.775 volts 4. dB P for Power (Watts) - 0.001 watt