Audio Lecture Notes

 

 

Sound Waves

1. What is Sound?
   • fluctuating air pressure: compression / rarefaction
   • How do waves work?
2. Loudness or intensity
   • amplitude: the extent of the change in air pressure
   • power or intensity of a sound can be measured in watts or dB
3. Pitch or Frequency
• cycles per second = Hz
• Threshold of hearing = 20Hz – 17kHz

Analog Recording

1. Microphones (transducers)
2. Loudspeakers
3. Magnetic Tape

Digital Recording

(diagrams)

1. ADC - DAC
2. Samples and sampling rate
3. Sampling resolution
4. Nyquist Theorem

Sound File Formats

1. AIFF - uncompressed Macintosh
2. WAV - uncompressed Windows
3. MP3 - MPEG4 compressed
4. AAC - Advanced Audio Coding

MIDI ( Musical Instrument Digital Interface)

1. What is it?
2. What do I need to use MIDI?