The Silent Problems of Noise

hello everyone

so before we begin i quickly want to

show you first something on the screen

well this is not me partying at my kid’s

birthday last year

but i’m actually trying to show you two

different scenarios of an acoustically

poor room an acoustically well designed

room all right

in the first balloon pop if you notice

it’s reverberating a lot

yeah and it’s difficult to converse with

people in such a situation

in the second instance the reflections

of sound are quite in control

and you will still be able to

communicate with people around you

without being bothered

with the quality of sound speaking of

quality

there are actually multiple dimensions

of sound and particularly sound

absorption

as a property i would like to talk to

you about the four

most important ones first as it is

referred as

sound pressure level which many of us

also commonly

refer to the decibels of sound which is

the net intensity of sound around us

and i’m sure with high sound pressure

level you can relate this with a crowded

shopping mall

on a weekend a fish market maybe

or even canteens school canteen

sometimes are

very noisy okay the second line here

is called as speech clarity when you

have

low speech clarity it means that words

are often getting jumbled with each

other and you are hearing the second

word

before the first word is ended the best

example here is

uh if you are in a closed metro station

it’s very difficult to hear speech

sometimes

if you’re in an empty room without

furnishings

clarity of speech is something which is

really lacking and the whole reason to

it is

this has to do with the early to late

reflections of sounds

in the given environment so sound

pressure level

speech clarity the third in line is

referred as

sound propagation which is about the

spread of sound from one point to the

other

the best example here is of an open

office workstation area

which is where by the virtue of the

design itself

you’re able to hear even conversations

that are happening at a far off place

one person over phone can still have the

potential to distract

many in the in the open office because

of sound propagation as a phenomenon

the last in line here is reverberance or

also called as reverberation time

and that i can explain by saying that

with higher revibration time

sound is taking a longer time to decay

from a given space

so logically for a working environment

like an office or a school building

you would need as low reverberation as

possible so that the feel of echo

doesn’t exist uh now an in-depth

analysis of all these four parameters is

quite crucial

if you wish to understand the silent

problems of noise

because only then you will be able to

appreciate when a certain good acoustics

treatment is being done

so let’s just take one of them as an

example sound pressure level

and and let’s see how does the human

hearing respond back

when there are changes in the decibels

so i’ve taken some sound files as

samples here

and i’m first going to play something

called as a pink noise i’m not sure if

you aware of it but there are different

types of noises

pink noise is taking as a standard

reference and we’ll reduce

three decibels from it and we’ll see how

do we hear or do we even notice these

changes

okay first pink noise

minus 3 db from this

are you able to hear the difference i’m

not too sure

unless your hearing is brilliant you

have the ears of a bat or an owl maybe

but i don’t think anybody in this

audience does so this is not

noticeable for sure all right let’s hear

it for -6 db

pink noise first

i’m reducing six decibels from this

you could notice it slightly yeah pink

noise once again

minus 10 db

minus 20 i’m sure this is noticeable

now the whole reason why i’m showing you

all of this is because

when we are trying to aim for an ideal

acoustics for a working environment

we are generally aiming for a reduction

of at least

five to six decibels or even more as a

solution because it’s only then

it’s noticed by the users of the space

and then they would start appreciating

the kind of change that is being done

if you further want to get in depth into

this what if we do

draw a comparison between the decibels

of sound on the y-axis

and the frequencies of sound on the x

okay i’m taking you back to the physics

of it

number of oscillations of a sound wave

anybody all right so what do we get

if we we put a comparison here we get a

weird shape like this

where if you see the hearing threshold

is approximately

20 db we generally do not hear sounds

under 20 decibels

when i closely whisper into your ear

that is about 25 db of sound

the upper threshold which is called as

threshold of pain is at 120 decibels

which is when you are practically

standing next to an aeroplane

that’s 120 db okay and it’s very

deafening and that’s why the ground

staff at the airport

will always have earplugs while they are

in the runway area

now the interesting part with in terms

of frequencies this is the band

that we are exposed to we generally do

not pick up sounds

which are lower than 75 or 60 hertz in

may in most cases

uh the best example which i always like

to give here is

have you seen the movie jurassic park

all of you

i’m sure most of you have seen the first

one okay you remember

the scene when there are those two kids

inside the large building and there’s a

dinosaur that comes behind

with the foot tapping noise and the

jelly starts shaking

in the hands of the kid you remember

that scene okay the reason the reason is

there you’re actually just

feeling the sound there you’re actually

not hearing it it’s

low frequency but very high in decibel

strength

that’s where you are actually able to

feel it or in a way hear it that’s our

hearing scale

above 20 000 hertz again suddenly our

hearing ability drops down

i’m not sure if you’re aware but there

are plug-in machines available in the

market to drive out mosquitoes

okay i have one at my house i’m not too

sure if it works

but the idea is it emits frequent sounds

at very high frequencies

which possibly the insects are hearing

we do not pick up those sounds

maybe the mosquitoes get some sort of a

headache and they move out of the room

i’m assuming

but dog whistles anybody pet lovers

you might certainly know this okay we

don’t hear those sounds it’s those

animals who can

reciprocate back to you in the right

manner now the most interesting part of

this graph

is when we place alphabets into this for

that matter any language but i’m just

considering english as of now

what happens when we place the english

alphabets in terms of their phonetics

the vowels a e i o u and in fact also

including y

in this case are placed on a higher

decibel band

and the consonants are below so how good

acoustics actually helps us

is by reducing the excess focus

on the vowels which is just adding

strength to my speech

and giving more emphasis on the

consonants which is where the real

information lies

i can explain that better can you try

and read these words on screen

don’t tell me this is tushar kapoor’s

language for you from the

bollywood industry yeah but i’m sure

it’s difficult you can’t you can’t make

that out okay

now can you make an attempt with the

next three words

it is possible to understand brilliant

okay so as you notice the first three

words had vowels

yeah the next head consonants so with

good acoustics

you’re reducing the excess focus on

vowels and giving more

emphasis on the real information or the

message of your speech

that’s the most important part uh if you

have curiosity y

p s f and t have been separated because

they are actually placed on a higher

frequency band

and the fact is as we grow older in our

lives

we start missing more of the words which

have the letters p

s f and t if you’re fortunate enough to

live with your grandparents at home you

might notice that often the sentences

that they miss

would generally have these words

included these alphabets included

word of caution here please do not try

and bother them tonight at home

with your experiments i don’t want to be

blamed for it okay

but now if this graph is too technical

for you

let’s let’s forget it at the moment but

the most important thing to remember is

when and why do we need good acoustics

so if the task at your hand is to ensure

that people are able to efficiently

communicate with each other

have meetings and have discussions out

of those four parameters if you remember

you need absolute control on the

reverberation time

and have high speech clarity there

that’s how you can relate to these

concepts all right

if the task at your hand is to ensure

that people are able to do their own

work

focus concentrate and do their

activities you need to ensure

that the sound pressure level is lowered

and the spread of sound

from one point to the other sound

propagation is also in good control

are you with me on that yeah but

the acoustics in open office as an

example

must support both communication and

concentration when required

so when these two people on screen if

they want to talk and have a

communication

of course the environment should allow

them without having too much of

reverberation or speech clarity issues

but the third person who is not a party

to that conversation

should ideally not be disturbed correct

i think with the technologies of today

human interactions are extremely crucial

to success

and good acoustics is only going to

enhance this for all of us

it was uh winston churchill in 1943

way back then when he made the statement

that we shape our buildings

and afterwards our buildings shape us so

i think his

emphasis on the quality of build spaces

around us is relevant even today

so what do you think shall we try some

of these aspects

right on us sitting here in this

auditorium

i would need your help to do a small

exercise where we’ll have some numbers

put up on screen

and i would urge you to try and remember

and memorize them

i know it’s almost a end of the day

it’s been a long tedx event

this is one of the interesting exercises

which i would urge you to participate in

are you with me okay the only thing that

i need beforehand

is please drop anything that is in your

hand just keep it on the desk sit with

your hands folded please

everybody please sit with your hands

folded we’ll have some numbers on screen

but with slight acoustic disturbance and

we’ll try and emulate how it typically

would happen

in an office and see how we are able to

memorize or

what’s our performance here are you all

ready here we go

as i said i’m trying to replicate the

office scenario so there’ll be some

background noise

some numbers in between fives and twos

and sixes maybe

sorry i’ll shut up

now can you jot it down on the piece of

paper you have with you

i would like to know how many of you

exactly got

this sequence just with show of hands if

you can help me

one two three four five six seven eight

nine 10 11 12 13 14 15

16 17 18 19 20 odd that i can quickly

count

standing here okay i’m assuming it’s

approximately 20 here

okay great uh that’s not the end of the

story yet

now we’ll do this once again with much

better acoustics

almost no disturbance let’s try it once

again

okay are you all ready once

last time let’s do this once again here

we go

can you quickly jot it down now

so would like to know how many of you

got this as a sequence or you felt you

are much better than the earlier one

probably you got four incorrect now it’s

just one or two incorrect ones

raise your hands please one two three

four five six seven nine eleven twelve

thirty five

many more okay i’ll lose my account here

but i can see at least about 200 percent

increase uh in our performance here

so round of applause for yourself you

did very well with good acoustics

okay but but uh the important thing here

is uh

a nice statement i would like to quote

from a german philosopher

mr arthur schopenhauer who said that

noise

is a torture to intellectual people and

with this experiment that we just did

i’m certainly sure it is all right uh

i would like to show you now a demo from

a very interesting study that we did

with

uh one of the prestigious schools in

mumbai where we had asked one of our

colleagues to stand at the teacher dies

and read out the same paragraph with the

same tonality

just before and after the acoustic

treatment and we actually had used a

class a category acoustic ceiling there

and that’s how the acoustics was managed

later on so first we’ll see

before before the acoustic treatment how

was the audibility inside

sound in nature for thousands of years a

human being’s

sense of hearing has been developed and

optimized for an outer environment

free from a natural sound reflexes

now he will speak after the acoustic

treatment being done

in nature for thousands of years a human

being sense of hearing has been

developed and optimized for a northern

environment

free from i’m pretty sure you could

notice the difference and now

this room is acoustically much better

and it is certainly

helping the overall student teacher

interaction and the quality of learning

i would say is certainly assured in

these situations

now often it’s not always about having a

ceiling treatment done there are many

other ways in which you can have the

acoustics well taken care of

like for example phone booths or silent

rooms as they call it

are very popular these days so if i have

to be loud over phone in my office

i should ideally not be disturbing

everybody around i should get a private

secluded space i can finish my task

and go back to the desk without

disturbing people

all right you can also work on the

immediate furniture on the screen itself

if that is made as absorptive as

possible

i think the overall acoustics is

certainly assured

so the way each of these screens would

help is the sound level would go on

dipping down at

distances and it will ensure that less

number of people are being affected by

by the noises around now i would like to

bring your attention to a very

interesting study that was

done at uh that was done by the

stress research institute in stockholm

where our team

was also involved in the acoustic

treatment the entire idea behind the

study was to find out

how sound affects people and for this

study there were two different flaws

identified

one was made with great acoustic

conditions the other way

poor acoustic situation after a set of

three weeks

the conditions were altered and after

another set of three weeks they were

brought back to the originality

now this crossover thing was done in

order to revalidate

the user responses every time the

acoustics is being changed

in this study about 151 employees

participated

and none of them were made aware as to

what acoustic changes are being done

so the study findings where good

acoustics leads to a reduction in

cognitive stress to up to 11 percent

better acoustic conditions also lead to

a reduction in perceived disturbance

to up to 16 percent so i think there was

a fair conclusion out of the entire

study

that it better sound management or good

acoustics around you

people are less stressed less disturbed

and they are able to perform much better

tilting walls anybody that’s another

very interesting concept where

architecturally

if you’re able to tilt one of the

building walls to an inner or the outer

angle

i think you’re just avoiding a

parallelly reflected sound back into the

room

and it is just deflecting it or

diffusing it to another angle and

possibly

allowing it to reach to the ceiling to

absorb the sound it’s a very interesting

and efficient way of managing acoustics

so related to this there are lots of

trends that we see today in the market

which i would wish to highlight

first offices are open not literally

but there are large vacant spaces where

many people are working at the same time

and we seldom have

cubicles or cabins these days virtually

all spaces are multi-purpose

which means there is enough adaptability

to the user needs these days

but at the same time there is high

demand for the efficiency out of these

spaces so how productive are these rooms

is often the question asked i think all

of this is also leading to tremendous

amount of creativity in designing

so i’m pretty sure that in near future

most of us are going to have offices

which are much better

and much comfortable to work around

so an office which probably was looking

like this traditionally

is fast getting transformed to being

like this

but if you see the noisier photocopier

machines are being separated from the

work area

with sound barriers or visual barriers

you have acoustic clouds

cloud ceiling panels we have carpets in

the traffic area

we have biophilic design plants and

shrubs around which also act as sound

diffusers

this is really helping in terms of

acoustics i’m not sure

visually it is as appealing to you as

possible but

as far as the sound quality is concerned

it is certainly

quite comfortable now for some reasons

if these aspects are

ignored in the beginning and if the

client wants to do

uh changes after occupancy we have seen

that it is often not just

difficult but also an expensive affair

and it is for these reasons why i would

urge you not to ignore

the silent problems of noise i think in

line with the theme of our tedx even

today

this is the very blind spot that i wish

to eliminate from our lives

in order to create better comfortable

working environments

for all of us thank you very much