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Teachers’ notes – Blocking sound
Synopsis
The final activity in this unit encourages learners to consider how people decide what
unwanted sound is and how they might respond to it. Initially, learners consider their own and
others ideas about how they react to different sounds. They explore how unwanted sounds
from inside and outside the home are blocked before considering when and why ear
protectors are worn. Learners suggest activities to determine which materials are the best for
blocking out sound before planning and carrying out an enquiry to find out. They predict the
decibel level of a range of familiar sounds and consider the damage that might be caused by
exposure to loud sounds. Finally, learners use maps and noise maps of Wales to explore
unwanted sound at a national level.
Curriculum links
How things work
4. how different sounds are produced and the way that sound travels
Skills
Communication: 1, 2 & 3
Enquiry – Planning: 1, 2, 3, 4, 5, 6 & 7
Enquiry – Developing: 1, 2, 3, 4, 5, 6 & 7
Enquiry – Reflecting: 5 & 6
Activities
Tab 1
This tab provides learners with a video clip of children talking
about how they react to sounds they dislike. Ask the learners to
think about and discuss the ideas they hear expressed on the
video and to share and consider their own ideas. The aim of this
tab is to provide learners with the opportunity to engage with the
notion that there are sounds that people do not like and that
these sounds are different for different people. Ask them to
consider how an unwanted and annoying sound for one person
might be someone else’s favourite sound. Encourage the
learners to consider how people usually react to an unwanted,
annoying or loud sound.
Tab 2

This tab provides learners with eight grey cards that can
be dragged and dropped in the middle of the screen. Four of the
cards each have a possible source of unwanted sound written on
them – ‘traffic’, ‘neighbours’, ‘hoovering’ and ‘TV’, whilst the other
four cards are blank and can be used for learners to write their
own ideas on. The aim of the tab is for learners to consider how
these unwanted sources of sound can be reduced by blocking
them out or by other means.
Tab 3
The aim of this tab is for learners to think about and discuss the
range of situations in which people wear some form of ear
protection. Learners are shown photographs of two different
types of ear protection on the tab. Ask them to identify the
different situations they know of when people wear ear
protection. Encourage learners to consider the reasons ear
protection is worn. They might also find out the recommended
decibel levels above which ear protection is advised, other
reasons for wearing ear protection and the problems that might
be caused by not wearing ear protection when appropriate.
Teacher’s notes:
The human ear is a complex and sensitive organ. It can detect
sounds in the frequency range 20Hertz (very low pitch) to
20,000Hertz (very high pitch). It is particularly sensitive to sounds
in the frequency range 500Hz to 5000Hertz – the so-called
speech frequencies that are vital for human communication. The
ear is able to deal with a wide range of volume (sound intensity)
from a pin dropping to an aeroplane taking off. However, the
inner ear in particular can be damaged by exposure to too much
sound energy – too much noise can cause damage. See tab
seven notes for further details.
A whisper is measured at about 30dB and normal conversation at
about 50dB. Any crowded place especially where there is music,
for example, can measure between 80 and 100dB. If you have to
shout to be heard then you are in an environment where the
sound level is only ‘safe’ for 30 minutes at the most. Evidence
suggests that the human ear can cope with sound levels below
85dB without too much difficulty for about eight hours. The ear
will suffer from Temporary Threshold Shift’ (TTS) after a short
time listening to loud sound. Ringing in the ears after a night at a
concert or disco is a good example of this. It is temporary and will
usually have resolved itself by the next day after the ears have
had an opportunity to rest. However, if this happened frequently
over a period of time then more permanent damage or
Permanent Threshold Shift’ (PTS) might occur. Initially, a
sufferer might have trouble understanding what others are saying
before more obvious hearing loss arises.
Following any permanent hearing loss, tinnitus may become a
problem. This affects the impulses sent to the brain via the
auditory nerve and can result in people hearing a constant
whistling or buzzing sound that might affect sleep and
concentration. There is no cure for permanent damage and
prevention is deemed to be the best policy. Using earplugs or ear
protectors and taking breaks in quiet areas are all advisable if
exposed to loud sound levels. Keeping well hydrated is also
advised as dehydration affects the function of the inner ear fluids.
Tab 4
The aim of this tab is for learners to think about and discuss
activities that could be used to investigate which materials are
the best at blocking sound. The tab provides learners with an
interactive ‘placemat’. Emphasis should be placed on the
generation of imaginative ideas and possibilities of how materials
might be fairly tested to determine how good they are at blocking
out sound. Different ideas can be discussed and considered with
the best idea or elements of more than one idea dragged into the
centre. This process might form the basis of learners thinking for
the enquiry on the next tab.
Tab 5
This tab follows the Plan – develop – reflect 3 in 1 tab structure.
Learners are required to plan an investigation to find out which
materials are the best for blocking sound. Ask the learners to
develop questions about the sound insulation properties of
materials that they might investigate. The aim of the tab is for
learners to explore the properties of a range of materials in
relation to them insulating sound and to continue developing their
skills of planning and carrying out an enquiry.
Tab 6
Learners are told that the loudness of sound can be measured in
decibels (db). A randomiser generates ten different audio files –
washing machine, football crowd, refrigerator, telephone, silence,
aeroplane, breathing, thunder, conversation and an electric drill.
There are two columns labelled ‘predict (db)’ and ‘result (db)’.
When learners click on the first audio file they hear the sound of
a washing machine. This sound is played to them and acts as a
reference point. A dash in the predict box prevents learners from
entering a number for the washing machine. Do not ask the
learners to predict the sound level for the washing machine,
encourage them to think about when they have stood near a
washing machine and how loud the sound was. When the audio
file stops the figure ‘70’ appears in the results column for washing
machine. Learners can now use this information as a basis for
considering what the values of the other sounds might be.
Explain to the learners that the sounds on the audio files are not
of the same intensity as if they were right next to them. The aim
of the tab is for learners to order sounds by loudness, to be
introduced to quantifying sound using the db and to gain an
understanding of the db range of the familiar sounds we hear.
Teacher’s notes:
The loudness of a sound is a subjective measure that is used to
describe how the ear perceives a sound. The sensitivity of the
ear is a factor when assessing how loud a sound is and might
vary between individuals. We tend to measure ‘sound intensity
‘using the decibel scale (db). Loudness can be thought of as a
complex combination of sound intensity and sensitivity. The ear
does not respond to an increasing sound intensity in a linear
manner but in a ‘logarithmic’ or ‘power of ten’ manner. Put simply
the sound intensity must increase ten times for the loudness of a
sound to double. This idea is often expressed in terms of musical
instruments – it takes ten guitars to sound twice as loud as a
single guitar. Expressed numerically, 20db does not sound twice
as loud as 10db; a sound intensity of 100db will sound twice as
loud as 10db.However, it must be noted that this is only an
approximation based on average hearing and is not an exact
mathematical relationship.
Another complication is that this relationship is only applicable
when dealing with the same sound. Thus, five guitars and five
flutes will not necessarily be twice as loud as either one guitar or
one flute.
Tab 7
The aim of this tab is for learners to activate their prior knowledge
about the damage that might be caused by listening to very loud
sounds over a period of time. The tab asks learners to record
their responses as ‘what I definitely know’, ‘what I think I know’
and ‘what I would like to know’. They should be encouraged to
search for answers to their questions.
Teacher’s notes:
A whisper is measured at about 30dB and normal conversation at
about 50dB. Any crowded place especially where there is music,
for example, can measure between 80 and 100dB. If you have to
shout to be heard then you are in an environment where the
sound level is only ‘safe’ for 30 minutes at the most. Evidence
suggests that the human ear can cope with sound levels below
85dB without too much difficulty for about eight hours. The ear
will suffer from Temporary Threshold Shift’ (TTS) after a short
time listening to loud sound. Ringing in the ears after a night at a
concert or disco is a good example of this. It is temporary and will
usually have resolved itself by the next day after the ears have
had an opportunity to rest. However, if this happened frequently
over a period of time then more permanent damage or
Permanent Threshold Shift’ (PTS) might occur. Initially, a
sufferer might have trouble understanding what others are saying
before more obvious hearing loss arises.
Following any permanent hearing loss, tinnitus may become a
problem. This affects the impulses sent to the brain via the
auditory nerve and can result in people hearing a constant
whistling or buzzing sound that might affect sleep and
concentration. There is no cure for permanent damage and
prevention is deemed to be the best policy. Using earplugs or ear
protectors and taking breaks in quiet areas are all advisable if
exposed to loud sound levels. Keeping well hydrated is also
advised as dehydration affects the function of the inner ear fluids.
Tab 8
This tab provides learners with an interactive ‘transport map’ of
Wales.
The map highlights the following: rivers, A-roads, motorways,
railways, ferry/barge routes, airports and the main cities and
towns. These categories appear in a box on the tab and can be
viewed on the map or hidden if clicked on. The inclusion of
and
buttons also allows the learner to ‘zoom in’ to any area of
Wales. Thus learners are able to look at how each category
affects their local area and Wales as a whole.
The aim of the tab is for learners to consider which areas of
Wales might be most affected by unwanted sound and to
consider the causes of these sounds and how they might be
reduced.
Tab 9
In 2006 and 2007 the Welsh Assembly Government (WAG) carried
out a mapping exercise to record noise levels from transport and
industry in Wales. It was deemed to be one of the largest IT projects
ever undertaken in Wales. The publishing of the noise maps was
seen as a move towards tackling the issue of excessive unwanted
sound and making Wales a quieter place. Encourage them to
consider what the purpose of the noise maps is and what they might
show. Ask the learners to explore the documents and maps on the
WAG website – they can be viewed and downloaded from the
(WAG) website using this link –
http://wales.gov.uk/topics/environmentcountryside/
epq/noiseandnuisance/environmentalnoise/noisemonitoringmapping/
majormaps/?lang=en