The class will start by answering classwork review questions regarding last week's work. This dealt with velocity, frequency and wavelength, as well as longitudinal waves. Using a small guitar, a lab type demonstration was done to determine the effect on the pitch of a sound due to the thickness of the vibrating string as well as the length of the vibrating string. Trarefactionshe thicker the string, the lower the pitch and the lower the Hertz. As the vibrating string was made shorter, the frequency increased, the wavelength decreased and the pitch increased. The transmission of a sound wave by longitudinal waves, consisting of a series of compressions and rarefactions was shown by using a diagram of a vibrating tuning fork and the compression and expansion of the air molecules. The vibrations of the tympanic membrane in the ear, at the same frequency as the sound waves, was used to explain briefly how we hear sounds of varying pitch.