What is sound?define, define, define!
• Changes in air pressure• Perception of the changes
We can hear from about 15 changes per second to 20000 changes per second (Hz)
“If a tree falls in a forest far from any sound detector (human ear,
microphone, etc.), does the tree's fall make any noise?”
“If a tree falls in a forest far from any sound detector (human ear,
microphone, etc.), does the tree's fall make any noise?”
Did you know?
Changes in air pressure perceived as sound are the same as…
…changes in air pressure discussed in meteorology
Did you know?
Changes in air pressure perceived as sound are the same as…
…changes in air pressure discussed in meteorology
Difference?Weather – greater magnitude, and change far more slowly
So many waves, but which is the one…
Nice animated examples: http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/waves/u10l1c.html
1.Period – time between two repetitions (duration of one cycle)2.Wavelength – the distance between corresponding points, from cycle to cycle as the wave repeats itself3. Frequency – how often the wave repeats itself during time unit4. Amplitude – how high and low wave oscillations are5. Phase – position of a wave at a certain time
Simple harmonic motion
Reflection the wave reflects away from the object
• Obstacle dimensions significantly larger than wavelength
• any change in the medium