Physics of sound
Loudness Pitch
Anatomy of our ears
How are sound produced?
10 second activity: 1. Make an “aaahhhhh” sound, meanwhile,
place your hand on the front of your throat2. Can you feel vibrations?
• Sounds are produced by VIBRATIONS
• When things vibrate, they move backwards and forwards very rapidly
• Musical instruments produce sounds in the similar manner
How does sound travel?
• Sound requires a MEDIUM to travel• Cannot travel through vacuum
Sound travels through solids
Sound travels through liquids
Sound travels through gases
Place your ear on one end of a table and tap the table.Can you hear?
Aquatic animals like dolphins make sound underwater
We can hear each other in air.
Speed of sound
• Sound travels at about 330 m/s in air.• It can travel faster in liquids and solids.
Supersonic jets
They travel faster than speed of soundSince Concorde's final retirement flight on November 26, 2003, there are no supersonic passenger aircraft left in service
How do we hear sounds?
• Sound travels in the form of WAVES• We cannot SEE sound waves, but we can
detect them when they reach our ears.
• The waves in the air are formed from VIBRATING AIR MOLECULES. In this way, energy is passed from molecule to molecule until it reaches our ears.
Anatomy of ears
• There are three important parts of our ear• Outer ear (collect sound waves)• Ear drum (between outer and middle ear)• Middle ear (contains ear bones which magnify
the vibrations and pass them to inner ear)• Inner ear (auditory nerves in inner ear detect
vibrations and change them into electrical signals, to be carried to the brain)
Anatomy of ear (picture)
Ear bones
Ear drum
Auditory nerve
Outer ear Middle ear
inner ear
Range of hearing
• Human ears has limited hearing range of sound frequencies (pitch)
• We can only hear between 20 Hz -20 000 Hz
• Mosquito tone: very close to 20 000 Hz• Animals have other ranges.
Rat repellent
Sms ring tone that parents and teachers cant hear!
Range of hearing of animals• Frog: 50 Hz – 10 000 Hz (lower than human)• Cat: 45 Hz – 64 000 Hz (higher than human)• Elephant: 15 – 12 000 Hz
Sound and music
• The highness and lowness of a musical note is called its FREQUENCY
• High pitch: high frequency• Low pitch: low frequency• Frequency is measured in Hertz (Hz)
Loudness and softness
• Sounds can be loud or soft• Loud sound has more energy than soft sound• Loudness depends on the size of vibrations• Large vibration large amplitude• Small vibration small amplitude
Amplitude