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