WEEK 12

Revision class 2

Threshold of pain 140dB

Threshold of hearing is 0dB

Ranges of Hearing

The accepted range of hearing is 20Hz-20kHz

The accepted dynamic range of hearing is 120dB

Stringed Instruments

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

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

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

Reed Instruments

Mechanical reed – sax, clarinet, bassoon

Lip reed – trumpet, trombone, tuba

Air reed – flute, recorder, organ pipe

Simple Waveforms

Sine

Square

Triangle

Sawtooth

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

Decibel Revision

• Reference values for Power, Voltage and SPL are:

1. dBSPL for Sound Pressure Level - 20µPa

2. dBV for Voltage - 1 volt

3. dBU for Voltage - 0.775 volts

4. dBP for Power (Watts) - 0.001 watt