Download Sound and the Ear

ETV “Junior Secondary Science” Programme
Sound and the Ear
Teachers’ Notes
Target Audience
Secondary 1 - 3
Duration
20 minutes
Production Aim
This programme is a teaching resource produced especially for enriching the
classroom teaching in S2 level of the Syllabus for Science (Secondary 1 – 3) prepared
by the Curriculum Development Council (1998).
The content of the programme serves to illustrate the following parts of the
Syllabus：
Unit 11 Sensing the Environment
Topic 11.5 – How we hear and Topic 11.6 – Limitations of our ears : All
Key Points, Content and Suggested activities, and
Topic 11.7 – Effects of noise pollution : All Key Points and Content.
Key Points
1.
2.
3.
4.
5.
6.
An introduction to the principles of sound creation and sound transmission.
An introduction to the concepts of frequency and magnitude of sound.
An introduction to the structure of the human ear and its function in detecting
sound.
An introduction to the ways of protecting our ears.
An introduction to the concept of noise pollution and its effects on human
body.
An introduction to the main points of Noise Control Ordinance and its
execution.
Content Outline
This programme is divisible into 7 segments as follows:
1. Creation of Sound
The film uses the performance of various musical instruments in an orchestra as a
clue to introduce the key question “how do instruments produce sound?” A violin,
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a piano, a set of drums and cymbals are then used as examples to show that object
vibrates to produce sound.
2. Transmission of Sound
The film shows first two loudspeakers vibrate when producing sound. The
loudspeakers are then connected to a transparent tube with foam beads inside. The
beads vibrate accordingly when the loudspeakers vibrate, showing sound is
transmitted through air and causes the beads to vibrate. A pump is used to pump
air out of the transparent tube to create a vacuum environment, the vanishing of the
sound shows that sound is transmitted using air as a medium. A tuning fork is put
inside a bell jar filled with smoke, showing that the fork vibrates to cause the
turbulence of the smoke. Computer graphics are then used to show how the
vibration of the tuning fork will cause the air particles to vibrate, thus explaining the
principle of sound transmission through air. The films shows lastly sound can also
transmit through both liquid and solid, and data are displayed to show that sound
travels fastest in solid, slower in liquid, and slowest in air.
3. Frequency of Sound
Using computer graphics and a tuning fork, the programme introduces the concepts
of vibration, frequency and Hertz. A signal generator is then used to produce
sound of different frequencies to show the limitation of our hearing ability, and to
introduce the concept and applications of ultra-sound.
4. Structure of the Ear
Using model and graphics, the film introduces the structure of a human ear:
external ear: pinna and external auditory canal
middle ear: eardrum, ear bones and Eustachian tube
inner ear: cochlea (a long tube coiled into the shape of the shell of a snail, it
is in fact an inner tube within an outer tube, the interior is filled
with liquid, and numerous sensory cells called hairy cells are
situated at the base of the inner tube).*
(*Only those parts of the ear associated with the perception of
sound are mentioned in the programme. The structure and
function of those parts associated with the sense of position
including semi-circular canals and vestibule will be dealt with in
another programme “Sense Organs”.)
5. Ear and Listening
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The film uses computer graphics to explain the function of the auditory parts of the
ear:
pinna: collects sound waves
external auditory canal: directs the sound waves towards the eardrum
eardrum: vibrates with the sound waves, and induces the vibration of the ear
bones
ear bones: transmit sound and amplify the magnitude of sound
cochlea: receives sound waves from the ear bones and transfers them into
ripples of the liquid in the outer tube; the ripples will induce the
vibration of the hair of the hairy cells at the base of the inner tube,
thus generating impulses and their interpretation in the brain as
‘sound’.
6. Protection of the Ear
The programme introduces several ways to protect the sensitivity of the eardrum:
- keeping the external auditory canal clean
- not probing the external auditory canal with hard objects
- opening mouth when hearing extra loud sound
- swallowing when taking an aeroplane or riding in an express elevator
- consulting a specialist when ears are feeling unwell.
7. Noise Pollution and Man
Daily examples are used to introduce the concept of noise pollution, the film also
introduces the unit of noise – decibel, and the instrument to measure it –
decibelmetre. A table on the source and strength of noise pollution prepared by the
Environment Protection Department (EPD) is used to show the noise level in
different environments. An Occupational Medical Officer from the Labour
Department explains the adverse effects caused by noise pollution on human health.
As noise level above 85 dB will cause damage to our hearing, a Noise Control
Ordinance is in force to control the following noises:
-
noise from domestic and public premises
noise from construction sites
noise from commercial and industrial premises
noise from Intruder Alarm Systems
noise from specified powered mechanical equipment such as hand-held
pneumatic hammers or air compressors
- noise from vehicles
The programme also introduces a number of important points in the Noise Control
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Ordinance, as well as how officers from the EPD carry out their work.
The film
ends with the Occupational Medical Officer explaining the ways of preventing
damage from excessive noise and the ways of protecting our hearing.
Suggestions for Utilization
1. The entire programme may be shown to students in one session to serve as a way of
consolidation after the teaching of the topic ‘Sound and the Ear’. It can also be
shown in three sections: segments 1 to 3 to help explaining and demonstrating the
physical properties of sound, segments 4 to 6 to help explaining the structure and
function of the ear, and segment 7 as reference material in discussion session on
problems of noise pollution.
2. The programme can also be shown in a S4/5 Biology/Human Biology lesson as a
starting point of the lesson, or as a way to motivate students.
3. The programme can also be used in an environmental education lesson from S1 to
S7 as reference materials during teaching and discussion of the problems of noise
pollution.
4. Teachers may spend 5 to 10 minutes before the show to lead students to discuss with
reference to the part “Preparation before viewing the programme” in the
Suggested Activities. After the show, teachers may spend another 10 to 15 minutes
discussing with students with a view to consolidating the concepts and principles
illustrated in the programme. Teachers are advised to refer to the part “Activities
after viewing the programme” in the Suggested Activities.
Suggested Activities
(The following activities are suggested for teachers’ reference only. Teachers may wish
to select suitable activities according to students’ abilities, the learning environment of
the class, and the teaching time available.)
Preparation before viewing the programme
1. Teachers may motivate the students by asking the students:
(a) if they are currently learning to play any instruments, and ask a couple of
the students to explain to the class how does a piano, a violin, an erhu(二
胡), a zheng(古箏), a di(笛) and a drum produce sound.
(b) what is our organ for hearing. If the students give “ear” as the answer,
teachers may then ask the students to suggest a simple experiment to
prove this (e.g. one cannot hear sound if one covers one’s ears).
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2. Teachers may explain the structure of the human ear to the students by showing
them a model ear; teachers may then ask the students to watch the programme
to see how the ear functions.
Activities after viewing the programme
A. Teachers may discuss with the students with reference to:
1. the properties of sound;
2. the structure and function of the human ear as an organ for hearing;
3. the ways to protect the ear.
B. Teachers may ask the students to go to the Environment Resource Centres
(Wan Chai Environmental Resource Centre, Queen’s Road, East, Wanchai,
Hong Kong. Tel: 2893 2856, and Tsuen Wan Environmental Resource Centre,
Tak Wah Street, Tsuen Wan, NT. Tel: 2944 8204) and the visitors’ centre (Tel:
2594 6013) of the EPD to collect the following information, and to prepare
either a notice board display or a project on the problems of noise pollution:
1. poster on Source and Strength of Noise Pollution prepared by the EPD.
2. pamphlet on Introduction to the Noise Control Ordinance prepared by the
EPD.
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