Making Sound Waves Sound waves are compressional (longitudinal) Caused by vibrations Are mechanical- can travel ONLY through matter Energy is transferred by the collisions between the particles

Speed of Sound Speed depends on the matter in which it travels Travel faster in solids and liquids than in gases. Speed through material increases as the temperature of the material increases

Loudness of Sound Loud sounds have more energy than soft sounds Intensity: the amount of energy that wave carries past a unit area each second. For example: A person standing close when the girl claps the cymbals would hear an intense sound. The sound would be less intense to the person far away. Sound with greater amplitude has greater intensity

Decibel Scale and Loudness Intensity of sound waves is measured in unites of decibels (dB) Softest sound a person can hear has an intensity of 0 dB Normal conversation has an intensity of 50 dB. Sound with intesities of about 120 dB or higher are painful to people. Loudness: the human perception of the intensity of soundwaves.

Frequency and Pitch Frequency of sound waves is determined by the frequency of the vibrations that produce the sound. Music scale- note C has a frequency of 262 Hz; E has a frequency of 330 Hz. People can hear frequencies between 20 and 20,000 Hz Pitch: the human perception of the frequency of sound. Sounds with low frequencies have low pitch, high frequencies, high pitch.

Reflection of sound Sound waves reflect off of material. Sound waves won’t reflect off soft surfaces (e.g. a theater) Reflection of sound can be used to locate or identify objects. Echolocation: the process of locating objects by bouncing sounds off them. E.g. bats and dolphins E.g. ultrasonic soundwaves in medicine