6.1 Loudness and Pitch of sound

• Loudness is a way to describe how quite or loud a sound appears
• Loudness depends on 2 variables:

  1. how much the object is vibrating; the greater the distance of each vibration, the louder the sound

  2. how far away the vibrating object is; the further away, the quieter the sound
• The greater the distance of each vibration,  the greater the distance that particles in air will be pushed and pulled
• Sounds get quieter because of energy dissipation
• Sound waves are vibrating air particles pass the energy of the vibrations away from the string in waves
• Amplitude the maxim distance that particles move, either forward or backward in a sound wave
• You can measure amplitude in 2 ways

  1. distance from zero to the top(peak) of the graph
  2. 2) distance from zero to the bottom(trough) of the graph
• In a sound wave

  • The peak is the highest point
  • The trough is the lowest point
• As the amplitude increases, the loudness of the sound also increases
• An oscilloscope is a tool that displays waveforms of sound waves
• Oscilloscope uses a microphone to detect the sound & produces a waveform of the sound on a screen
• Small amplitude = quiet sound
• Loud amplitude = Loud sound
• Pitch is how high or low the sound appears on a musical scale
• Pitch changes because the speed of the vibrations also changes
• The faster the vibrations, the higher the pitch of the sound
• Frequency is the number of vibrations in each second
• The speed of vibrations is measured by the number of complete vibrations per second
• As the frequency of a sound wave increases, the pitch of the sound also increases
• Frequency is measured in a unit called hertz or Hz
• A frequency of 500Hz means 500 complete vibrations happen every second
• The amplitude of low and high pitch are the same means their loudness are the same
• Vibrating objects that are shorter make higher pitch sounds than those are longer