1. Properties of Sound Physical Science Ms. Pollock 2009 - 2010

2. Intensity and Loudness Quieter sound waves carry less energy than louder sound waves. Energy – amplitude; depends on number of molecules in compressions and rarefactions http://universe-review.ca/I13- 16-soundwave.jpg

3. Intensity http://windchimes.co.za/phot os/sound_intensity_levels.gif Amount of energy that flows through a certain area in a specific amount of time Reduction in volume = reduction in intensity Influences distance sound can be heard Decreases with distance

4. Loudness Human perception of sound intensity High intensity = more energy, greater loudness http://www.tpub.com/neets/b ook10/NTX1-14.GIF

5. The Decibel Scale Loudness is a HUMAN perception. It will vary from person to person. Intensity of sound measured in decibels (dB) Faintest sounds (whisper) 0 dB Loudest sounds (jet) 150 dB Above 120 dB may result in hearing loss and pain

6. The Decibel Scale http://www.buyempblog.com/wp- content/uploads/2009/03/decibel-scale.gif

7. Pitch Pitch – how high or low a sound seems to be High frequency = high pitch Greater vibration of parts of ear Healthy human ear able to hear 20 Hz to 20,000 Hz but is most sensitive to 440 Hz to 7,000 Hz Ultrasonic and infrasonic waves not heard, but used. Medical treatments

8. The Doppler Effect http://ffden- 2.phys.uaf.edu/212_fall2003. web.dir/nathan_earls/doppler _effect.gif Change in pitch or wave frequency due to a moving wave source Lengths of compressions and rarefactions altered, so pitch changed Occurs in sound waves and electromagnetic waves (radar)