F2 - SEM2 - Sensing the Environment - 10.3 Hearing Flashcards
Why is hearing important us?
Production of sound
- allow us to communicate
- avoid danger
Production of sound
How sound is produced?
Production of sound
vibration of object produces sound
Production of sound
Explain how sound is produced by musical instruments below
Drum, Violin, Dizi, Guzheng, Trumpet, Piano
Transmission of sound
vibration of string - Violin, Guzheng, Piano
vibration of letter parts - Drum
vibration of air columns - Dizi, Trumpet
Transmission of sound
Explain how sound is transmitted
Transmission of sound
vibration of object
-> air particles in the surrounding vibrates
-> vibrations are transmitted through air to our ear
-> ear detect the vibration of air particles
-> we hear the sound produced
Transmission of sound
What is needed for sound to travel? please give some examples.
Transmission of sound
medium is need for sound to travel
e.g. gases, liquids and solid
Does sound travel at same speed in different medium?
Compare the speed of sound tranmitted in solid, liquid and gases
Transmission of sound
- sound travels at different speed in different media
- fastest in solid, slower in liquid and slowest in gases
Transmission of sound
Can sound travel through vaccum? Why?
Transmission of sound
- sound cannot travel through vaccum
- no particles are present to transmit the vibration of objects
Transmission of sound
What are the 6 structures of our ear? How do we hear?
Structure of our ear + How we hear?
- Pinna - collect sound in the surrounding
- Ear canal - sound travels along ear canal and hits the eardrum
- Eardrum - sound causes the eardrum to vibrate
- Ear bones - ear bones amplify the vibration of eardrum and pass them on the inner ear
- Cochlea - specialised sensory cells in Cochlea for detect vibration and send out message
- Auditory nerve - message are sent along the auditory nerve to brain for interpretation
Structure of our ear + How we hear?
What is frequency and its unit?
Audible frequency range of humans
- Frequency is number of vibration per sound
- unit is Herz
Audible frequency range of humans
How is frequency related to vibration and pitch?
Audible frequency range of humans
higher frequency
=> higher vibration
=> higher pitch
Audible frequency range of humans
What is the audible frequency range of human?
Audible frequency range of humans
- 20 to 20,000Hz
- different persons have different ranges
- become narrower when getting old
Audible frequency range of humans
What is the audible frequency range of below animals?
dog, dolphin, bat
Audible frequency range of humans
dog - 67 to 45,000Hz
dolphin - 75 to 150,000Hz
bat - 1,000 to 150,000Hz
Audible frequency range of humans
What is the frequency of ultrasound?
Audible frequency range of humans
over 20,000Hz
Audible frequency range of humans
What is the frequency produced by dog whistle?
Audible frequency range of humans
22,000Hz
Audible frequency range of humans
What is noise?
Noise pollution
unwanted sound
Noise pollution
What are main sources of noise in Hong Kong?
Noise pollution
- traffic
- construction works
- machinery
Noise pollution
What is the unit of sound level or loudiness of sound?
Noise pollution
Decibels (dB)
Noise pollution
What is the sound level of each below?
country park
normal talking
moving MTR / road drilling
Noise pollution
- country park - 0 to 40 (LOW)
- normal talking - 40 to 80 (MEDIUM)
- moving MTR / road drilling - over 80 (HIGH)
Noise pollution
What is the tools used to measure the sound level / loudiness of sound?
Noise pollution
- decibel meter
- sound level meter
Noise pollution
What are the effects of noise pollution?
Noise pollution
- disturb our sleep and cause mental stress
- hurt our ear - prolonged exposure to noise over 85dB damaged specialised sensory cells in the cochlea and damages cannot be recovered
Noise pollution
How to protect our ears?
Noise pollution
- stay away from noise places
- wear ear protector during nosiy work
- keep the volume low when using earphone
- don’t pick year ears with hard objects
Noise pollution
What are the actions taken by government to control noise pollution?
Noise pollution
- build noise barrier along busy roads and railways
- use special material to cover road surface
- limit the time for noisy contruction works
Noise pollution
