Johnson Ch1.3

1.3 Types of Sounds

1.3.1 Simple periodic waves

• periodic
  • simple: sine waves
    • when we’re very young
    • children; sinusoidal
    • women > men
    • rarely occur but important > because more complex sounds can be described as combinations of sine waves
    • 
    • 
  • 1) frequency: sinusoidal pattern repeats per unit time
  • cycle: each repetition of the pattern is called
  • period: the duration of a cycle
  • hertz(Hz): frequency can be expressed as cycle per second
  • = 1/T (T: period in seconds)
  • 2) amplitude: the peak deviation of a pressure fluctuation from normal, atmospheric pressure
  • 3) phase: the timing of the waveform relative to some reference point

1.3.2 Complex periodic waves

• Complex periodic waves
  • 반복되는 파형 패턴 > 단순 주기파와 비슷, 주기를 가짐
  • 최소 두 개 이상의 사인파로 이루어짐
  • fundamental frequency(F0)
• 기본주파수와 최대공약수(GCD):
• Fourier’s theorem

1.3.3 Aperiodic waves

• white noise
• transients(과도음): 짧고 갑작스럽게 발생하는 압력 변화 / 오래 지속되거나 반복되지 않음
• impulse