Loudness and amplitude

• The loudness of a sound on an oscilloscope is shown by the height of the waves. This is called the amplitude.
• A quiet sound:

  
• A loud sound but low pitch:

  
• A high pitch:

  
• The larger the amplitude of the wave, the louder the sound.
• The more waves on the oscilloscope trace, the higher the frequency and pitch.
• An echo happens when sound bounces off an object. Bats use echoes to find prey. If the sound isn't reflected, the object absorbs it and heats up a little.
• amplitude - volume
• frequency - pitch