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Junior(1)

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Junior(1) ...

    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. An introduction to the principles of sound creation and sound transmission.

    2. An introduction to the concepts of frequency and magnitude of sound.

    3. An introduction to the structure of the human ear and its function in detecting

    sound.

    4. An introduction to the ways of protecting our ears.

    5. An introduction to the concept of noise pollution and its effects on human

    body.

    6. 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,

    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

    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 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

    ), a zheng(古箏), a di() 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 ones ears).

    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, Queens 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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