Hobbies And Interests
Sound Waves
Music is heard when sound waves vibrate. Sound waves are formed when instruments are plucked, as with a guitar -- hit, like on a drum -- or blown, as through a tuba. Music from instruments travel through the air at a frequency which is dependent on speed and wavelength. A guitarist, for example, controls the frequency or pitch of his guitar strings by pressing the fret on the neck of the guitar, while strumming the strings with his other hand.
Air
The speed of the sound wave depends entirely on the properties of the air. The temperature is one of the greatest factors affecting the speed of sound through air: and humidity, which is how much moisture is in the air, is another factor. Higher temperatures cause air molecules to bounce faster, causing sound waves to travel faster. In low temperatures, sound travels slower, while high humidity causes sound to travel slower, because of the density of the water vapor in the air.
Expansion
The musical instruments themselves change in higher and lower heat. Higher heat causes wood to expand. Sometimes the expansion is irreversible. A piano may expand from the heat, causing the strings to change slightly in position. Musical instruments are so finely tuned, that musicians can hear the differences right away. Nylon strings on a guitar expand in heat causing the pitch to or frequency to go down. Metal instruments also expand, causing sound to become higher -- or sound sharper.
Science Experiments
To learn more about the effects of temperature on sound, you can perform some simple experiments. One experiment uses three PVC tubes. One tube is placed into cooled water, one place into hot water and one is kept as a control, at room temperature. Blow across the opening of each tube. The cooled tube sounds flatter and lower pitched, when compared to the room temperature tube, while the heated tube sounds sharper and higher pitched.