1. When a vibration or an oscillation repeats itself, back and forth, over the same path, the motion is called periodic. Examples: swing, vibrating spring, grandfather clock, different types of waves ALL Waves carry energy Periodic Motion

2. Different types of waves around us: Ocean waves: Greeting or cheering waves: Shaking a rope waves: Compressing a slinky waves: Electromagnetic waves (radio; TV; X-rays; microwaves) Mass on a spring; Circular motion and pendulum waves: http://positron.ps.uci.edu/~dkirkby/music/html/demos/SimpleHarmonicMotion/index.html http://positron.ps.uci.edu/~dkirkby/music/html/demos/SimpleHarmonicMotion/index.html http://www.youtube.com/watch?v=eZm_-2O8ovI&annotation_id=annotation_120510&feature=iv&src_vid=7_AiV12XBbI

3. A sound wave is produced by a vibrating object. As a sound source (guitar string; tuning fork, etc.) vibrates, it sets surrounding air molecules into vibrational motion. eardrum Guitar string Tuning fork …and last but not least: Sound waves

4. Sound waves in 1 and 2 dimensions: http://positron.ps.uci.edu/~dkirkby/music/html/demos/PlaneWave/SoundGraph.html

5. Sound Waves

6. Sinusoidal Nature of Waves All types of waves could be described using trigonometric functions: Where A is the amplitude;  is the angular frequency (in radians per seconds) and  is the phase shift

7. Practice with computer simulated sound: Datastudio software

8. Sound in everyday life Pitch: related to frequency. Audible range: about 20 Hz to 20,000 Hz; Ultrasound: above 20,000 Hz; Infrasound: below 20 Hz Loudness: related to amplitude of the sound wave There are two different ways to measure loudness: 1. Using the subjective sensation of a human being; 2. Using the physically measurable quantity “intensity” of sound;