Transcript Interactions of Sound Waves

Sound Quality and Applications
Music vs. Noise
• Music
– sounds that have a pleasing quality, a definite
identifiable pitch, and rhythm
– musical instruments use standing waves to
produce sound.
– Types of musical instruments
• percussion (drums, bells, cymbals) –
vibrations of membranes or metal
• stringed (guitars, violins) - vibrations of
strings
• woodwind and brass (flutes, pipe organs,
trombones, clarinet) – vibrations of air
columns
– many instruments sound better and louder
when two objects are vibrating at the same
frequency; this is called resonance
• example: both the guitar strings and body
vibrate
• Noise
– sounds that have no pleasing quality,
no identifiable pitch, and no
relationship between high and low
pitches
– when noise reaches a level that cause
pain or stress it becomes noise pollution
Applications of Sound
• SONAR
– uses ultrasonic waves in a system called
SOund Navigation And Ranging
– determines distance by the time it takes
sound to bounce back; formula is d = v · t
– Uses of SONAR
• map the ocean
floor
• military
• Bats and Whales
– send out ultrasonic waves that bounce back to
locate objects just like SONAR
• Medical
– Use ultrasound waves to create sonograms
• very high frequencies (1-15 million Hz)
• sound travels at different speeds through
materials with different densities (bonehigh, tissue-low density)
• used in medical facilities to get a picture
the human structure, including a fetus that
is growing
• can even be concentrated to destroy bad
tissue