Sounds

• Sound waves


  Longitudinal waves created from a vibrating source
• Sound waves


  • They are mechanical waves, which means they need a medium to propagate
  • They can propagate through solids, liquids, and gases
• Sound travels fastest


  In solids, followed by liquids, then gases
• Reason for speed difference


  Arrangement and spacing of particles in each medium
• Sound cannot be heard in outer space
• Pitch


  Highness or lowness of sound, determined by the frequency of the wave
• The human ear can sense frequencies between 20 Hz and 20,000 Hz
• Infrasonic frequencies


  Frequencies below 20 Hz
• Loudness


  How soft or intense the sound is, determined by the amplitude of the sound wave
• Sound intensity


  Measured in decibels, with 0 dB being the threshold of hearing and 120 dB being the threshold of pain
• Loudness is a psychological sensation that differs between people
• Timbre or tone quality


  How we identify the difference between the quality of tone of one instrument from another, even if they have the same pitch and loudness
• Timbre depends on the waveform of the sound wave