VELOCITY OF SOUND At STP sound travels 3.31 x 10 2 m/s > It’s 4 times faster in water. > It’s 15 times faster in metal. Will change due to temperature: v = 331m/s + 0.6(T) (T is in Celsius)
Sound is a range of wave frequencies that the ear is sensitive to. (20Hz- 20,000Hz) Infrasonic sound- Sounds lower than 20Hz Ultrasonic sound- frequencies higher than 20,000Hz Transmission Range- frequencies an organism can produce ( humans 85- 1000Hz)
How does the ear work? The outer ear “catches the sound waves”. The middle ear takes the sound waves and “vibrates” the eardrum. The inner ear sends the messages to the brain. Middle Ear Inner Ear http://www.youtube.com/watch?v=pCCcFDoyBxM Outer Ear
FREQUENCY Frequency- the number of vibrations per second. How the ear identifies this vibration is called pitch. Pitch and frequency are directly proportional. High Pitch Low Pitch http://www.animations.physics.unsw.edu.au/jw/sound-pitch-loudness-timbre.htm
FUN INFO The phone company uses a combination of frequencies to make a unique sound for each number on the phone. #1 is 687Hz and 1209Hz #2 is 687Hz and 1336Hz #3 is 687Hz and 1477Hz http://soundbible.com/tags-dial.html
AMPLITUDE Amplitude- the maximum displacement of the particles from equilibrium. Amplitude determines the intensity of the sound and how loud it is. http://www.animations.physics.unsw.edu.au/jw/sound-pitch-loudness- timbre.htm
SOUND INTENSITY Sound Intensity- the rate of flow of sound energy from a source. Measured in decibels or watts/meter 2 According to OSHA 85dB and higher will produce permanent hearing damage.
HOMEWORK FROM TEXT BOOK pg 369 #21-23 and #25-30 Show all formula’s and calculations!