Sound waves and hearing

Question 1

What are sound waves

Answer 1

• Vibrations that pass through a medium
• Longitudinal waves so consist of compressions and rarefractions

Question 2

What are compressions

Answer 2

• Regions where vibrating particles are closest together

Question 3

What are rarefractions

Answer 3

• Regions where vibrating particles are furthest apart

Question 4

How do sound waves pass through a solid

Answer 4

• Sound waves cause particles inside the solid to vibrate
• These vibrations are passed on to neigbouring partivles
• The sound wave travels through the solid

Question 5

How is the speed of a sound wave determined

Answer 5

• The more densley packed the particles, the faster the sound wave is transmitted

Question 6

At what speed does a sound wave travel in different mediums

Answer 6

• Fastest in solids
• Slower in liquids
• Slowest in gases
• Not at all in a vacuum

Question 7

What changes in a sound wave along with the speed

Answer 7

• As sound waves travel between mediums, frequency does NOT change
• As V = f X wavelength, when V changes, wavelength also changes

Question 8

What happens to a wave when moving from a solid to a liquid

Answer 8

• The sound wave gets slower
• The wavelength decreases

Question 9

What can happen to sound

Answer 9

• Sound can be refracted, absorbed and reflected
• Sound reflects best by hard and flat surfaces (known as echoes)

Question 10

How do human ears work

Answer 10

• Sound wave travels along ear canal
• Ear drum vibrates due to sound wave
• Vibrations pass along ossicles (3 bones), through sem-circular canal and into cochlea
• Cochlea converts sound waves into electrical signals
• Electrical signals are sent to brain via auditory nerve

Question 11

How is different sound interpreted by the brain

Answer 11

• Higher frequency = higher pitch
• More intense signal = louder sound