Wavelength

• A wavelength is the length of one complete wave from crest to adjoining crest or from trough to adjoining trough. These crests and troughs are the maximum displacements above and below an equilibrium line.
  
  

Frequency and Pitch

• Since sounds travel at a constant speed through a given medium (assuming constant temperature and pressure), changes in wavelengths change the frequency of the sound. Therefore, the pitch can be equated to the frequency of the sound.
  
  

Musical Notes

• Musical notes vary in pitch by about one hertz. This corresponds with the inability of the human ear to distinguish frequencies that are less than one hertz in difference.
  
  

Speed of Sound

• The speed of sound traveling through a substance is determined by the substance and not the frequency of the sound wave. For example, a sound at 440 Hz will travel through air (for constant temperature and pressure) at the same speed as a sound at 220Hz. This means two different notes played at the same time by two different equidistant instruments in an orchestra will be heard by a listener at the same time.
  
  

Range of Human Hearing

• The human ear is able to detect frequencies between 20 Hz and 20 MHz. This range does vary between individuals and normally decreases as a person ages.