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You should spend about 2 0 minutes onQJ$estiuuso 27-40, wh ich are based on Reading P assage 3

below.

In general, it isplausible to suppose that we should prefer peace and quiet to ! l 1o is~oAndyet most or us havehad the expe rience of havin g to adjust to sle~ping in the mountams orthe countryside because itwas initially 'too quiet', an experience that suggests thathumans arecapable of adapting toa wide range of noise lev els.Research supports thisview,For example, G lass and Singer (1972)eJ{;posedpeople to short bursts of very loud

noise and then measured their abilityto work out problems and their physiologicalreactions to the noise. The noisewas quite disruptive atfirst , but after about four minutesthe subjects wer edoing just as wellon their tasks as control su~jec ts who were not exposedto noise. Their physiological arousal also declined quickly to the same levels as those ofthe control subjects.

But there are limits toadaptation and Joud noise becomes mo re troublesome ifthe personis required to concentrate onmore than one task. For example, high noise levels interferedwith the performance of subjects who wererequired to mo nitor three dials at a time, atask not unlike that of an aeroplane pi lot or an airwtrafficcontroller (Broadbent, 1957),Similarly, noise did not affect a subject's ability to track a moving line with a steeringwheel, but it did interfere with the subj~.ct'sability to repeat numbers while tracking

(Finkelman and Glass,

1970).Probably the most significant finding fromresearch on noise is that i ts predictability ismore important than how loud itis.W e are much more ab~e to 'tune out' c~mmic

backgro und noise , even if iti s quite loud, than to work under circumstances withunexpected intrusions of noise.In the Glass and Singers tudy, inwhichsubjects w .e re

exposed to bursts of noise as they wo rked on t.ta"k. som e subjects heard loud bursts andothers heard soft bursts. For some subje cts, the bursts werespaced exactly one minuteapart (predictable noise); others heard thesame amount of rnoise o~:eran,but the r.mlf'sas

Loud noise 40.1 31.8 35.9

Soft noise 36.7 27.4 32 .1

Average 38.4 29.6

I~

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occurred at random intervals (unpredictable noise). Subjects reported finding thepredictable and unpredictable noise equally annoying. and all subjectsperformoo atabout

the samelevel during the noise portion of theexperiment. But thedifferent noise

conditions had quite different after-effectswhen the subjectswere!required toproofread

written material under conditions of no noise.As shown inTable 1 the unprediew.b!e

noise produced more errors inilielater proofreading task than predictable noise; and soft,

unpredictable noise actually produced slightlymore errors on this task than the loud,predictable noise. .

Apparently, unpredictable noiseproduces more fatigue than predictable noise. but it takesa while for this fatigue totake itstoll onperformance.

Predictability is not the onlyvariable that reduces or eliminates the negative effectsof

noise. Another iscontrol. If theindividual knows that heorshecancontrol the noise, this

seems to eliminate both its negative effects at thetime and itsafter-effects. This is true even

if the individual never actually exerciseshis or heroption to turn thenoise off (Glass and

Singer. 1972).Just the knowledge that onehas control issufficient.

The studies discussed sofar exposed people tonoise foronlyshort periods and only

transient effects were studied. But the major worry about noisyenvironments isthat living

day after day wi.thchronic noise may produce serious, lasting effects.One study, suggesting

that this worry is a realistic one,compared elementary school pupils who attended schools

near Los Angeles's busiest airport with students whoattended schools in quiet

neighbourhoods (Cohen etal., 1980). It was found that children from the noisy schools

had higher blood pressure and weremore easily distracted than those who attended the

quiet schools. Moreover~ therewasnQevidence ofadapt~rr,mtyto he noise. In fact, the

longer the children had attended tne noisy schools, the more distractible they became. Theeffects also seem to be longlasting. Afollow-up study showed that children who were

moved to less noisy classrooms stillshowedgreater distractibility one year later than

students who had alwaysbeeninthe quiet schools (Cohenet ai, 1981). It should benoted

that the two groups of children had beencarefully matched bythe investigators so that

they were comparable in a ge, ethnicity. race,and socialclass.

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Questions 27.....29

27 The writer suggests that people may have difficulty sleeping in the mountains because

I,hu mans do not prefer peace and quiet to noise.

R they may be exposed to short bursts of very strange sounds .

C humans prefe'r tohean'lcertain amount of nO ise.while they sleep.D. they may have adapted toa higher noise levelin the city.

28 In noise ex.periments, Glass and Singer found that

G) problem-solving ismuch easier under quiet conditions.

~

., ph ysiological arousal prevents the a bility to work.

~, bursts o~ Ilois,edo not seriously ?isrup t ?roblem-:ol~ing.in the long term.D the physlOlogICal a.rou sal o f con trol subjects decbnea qmckly.

29, ,Researchers discovered that,bigh noise levels re not likely to interfere with the~'" " ' ,

. \ Sll(,;C essful'perform~ si~ql~task:~ .. ..'f; tasks of p~Iotsor aI r on roilers. ~il 1C abilityto repeat nu' > ersw >Iet r a eEn gm~ving es.

ability totnonitotthree dials~atonce.

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Questions 30-34

Glass and Singer (1912) showed that situations in which there lsintensa noisa haveless effect on performa.nce than circumstances in which 30, , , noiseoccurs. Subjects were divided into groups to perform a task. Some heard loud burstsof noise, others soft For some subjects, the noise was predhctabl,e,while for others itsoccurren~e was random, All groups were exposed to 31 ,...................... noise, The

predictable noise'group " the unpredictable noise group on this task.

In the second part.of the experiment, the four groups w ere given a proofreading taskto complete under conditions of no noise. They were required to check writtep materialfore rro rs. T he gro up w hich h ad b ee n exp osed to u np re dicta ble no ise 3 3 .the group which had beenexposedJo predictable noise. The group Which had beenexposed to loud predictable noise performed better than those who had heard soft,unpredictable bursts. The results suggest that 34 nOise producesfatigue but that this manifests itself later.

A no control overB u ne xpe ctedC IntenseD the same amount o f E performed better thanF per10rmed at about the same level asG no

H showed more Irr itat ion thanI m a d e m o r e m i st ak e s t h an

J different types of

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Qllestions 35-40

Long-term exposure to noise can produce changes in behaviour which can still beobserved a year tater.

Th e prob lems associated with exposure to noise do not arise if the su bject knows theycan make it stop.

@Expo sure tohigh~pitched noise results in more errors than exposure to low~pitchednoise.

cj2) Subjects find itdifficu lt to perform three tasks at thesame time when exposed to noise.6>No ise affects a subject"s cap acity to repeat numbers while carrying out another task.

@

@(jj)

Subjects expo sed to noise find it di fficult at first to concentrate on problem-solvingtasks. .

List of Researchers

A Glass and Singer

B Broadbent

C Finkelman and Glass

D Cohenet aL

E None of the above

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