2. The Physics of...

3. What is sound? zReview of sound as an example of a longitudinal, mechanical wave zThe sound spectrum: infra-sonic (< 20 Hz) sonic (20 Hz - 20 kHz) ultra-sonic (> 20 kHz) zHow much energy does a sound wave carry? - a simple demo

4. So, how good is YOUR hearing? zLet’s take another look at the “hearing a pin drop” activity and try to estimate the power that our ears responded to...  Power how can we estimate  t?

5. The Decibel (dB) Scale  Our ears are able to accommodate an enormous range of sound intensities. To express this in a convenient, mathematical form the Decibel Scale was developed: where  is the sound intensity level or dB level. I 0 is the threshold for acute hearing and is set as: I 0 = 1.0 x 10 -12 W/m 2.

6. Anatomy of a Sound Wave zWhat is the amplitude of a typical sound wave? zHow much of a pressure variation is produced by a sound wave? zHow does sound intensity vary with distance zHow does motion affect sound?

7. Wave Interference in 2D... zConcept of path length and path difference zNodes and Anti-Nodes in 2D an applet simulation demo zAn application - hot spots in your living room

8. The Doppler Affect zMotion affects received wavelength: ymoving source see applet demosee applet demo ymoving listener zApplication of this: xmedicine - angiodynography xBiology - “Bat” Sonar xMeteorology - Doppler radar xAstronomy - measuring motion

9. Shocks... zConditions for the formation of shocks yMach Angle yShock Heating yPorpoise “DeathRay”? yBull Whips and Towel Snaps!