Why you don't like the sound of your own voice

If you ask evolutionary biologists

when did humans become humans,

some of them will say that,

well, at some point
we started standing on our feet,

became biped and became
the masters of our environment.

Others will say that because our brain
started growing much bigger,

that we were able to have
much more complex cognitive processes.

And others might argue
that it's because we developed language

that allowed us to evolve as a species.

Interestingly, those three
phenomena are all connected.

We are not sure how or in which order,

but they are all linked

with the change of shape of a little bone
in the back of your neck

that changed the angle
between our head and our body.

That means we were able to stand upright

but also for our brain
to evolve in the back

and for our voice box to grow
from seven centimeters for primates

to 11 and up to 17 centimetres for humans.

And this is called
the descent of the larynx.

And the larynx is the site of your voice.

When baby humans are born today,
their larynx is not descended yet.

That only happens
at about three months old.

So, metaphorically, each of us here

has relived the evolution
of our whole species.

And talking about babies,

when you were starting to develop
in your mother's womb,

the first sensation that you had
coming from the outside world,

at only three weeks old,
when you were about the size of a shrimp,

were through the tactile sensation

coming from the vibrations
of your mother's voice.

So, as we can see, the human voice
is quite meaningful and important

at the level of the species,

at the level of the society --

this is how we communicate
and create bonds,

and at the personal
and interpersonal levels --

with our voice, we share much more
than words and data,

we share basically who we are.

And our voice is indistinguishable
from how other people see us.

It is a mask that we wear in society.

But our relationship with our own voice
is far from obvious.

We rarely use our voice for ourselves;
we use it as a gift to give to others.

It is how we touch each other.

It's a dialectical grooming.

But what do we think about our own voice?

So please raise your hand

if you don't like the sound of your voice
when you hear it on a recording machine.

(Laughter)

Yeah, thank you, indeed,

most people report not liking
the sound of their voice recording.

So what does that mean?

Let's try to understand that
in the next 10 minutes.

I'm a researcher at the MIT Media Lab,

part of the Opera of the Future group,

and my research
focuses on the relationship

people have with their own voice
and with the voices of others.

I study what we can learn
from listening to voices,

from the various fields,

from neurology to biology,
cognitive sciences, linguistics.

In our group we create
tools and experiences

to help people gain a better
applied understanding of their voice

in order to reduce the biases,

to become better listeners,

to create more healthy relationships

or just to understand themselves better.

And this really has to come
with a holistic approach on the voice.

Because, think about all
the applications and implications

that the voice may have,
as we discover more about it.

Your voice is a very complex phenomenon.

It requires a synchronization
of more than 100 muscles in your body.

And by listening to the voice,

we can understand possible failures
of what happens inside.

For example:

listening to very specific
types of turbulences

and nonlinearity of the voice

can help predict
very early stages of Parkinson's,

just through a phone call.

Listening to the breathness of the voice
can help detect heart disease.

And we also know that the changes of tempo
inside individual words

is a very good marker of depression.

Your voice is also very linked
with your hormone levels.

Third parties listening to female voices

were able to very accurately
place the speaker

on their menstrual cycle.

Just with acoustic information.

And now with technology
listening to us all the time,

Alexa from Amazon Echo

might be able to predict
if you're pregnant

even before you know it.

So think about --

(Laughter)

Think about the ethical
application of that.

Your voice is also very linked
to how you create relationships.

You have a different voice
for every person you talk to.

If I take a little snippet
of your voice and I analyze it,

I can know whether you're talking
to your mother, to your brother,

your friend or your boss.

We can also use, as a predictor,
the vocal posture.

Meaning, how you decide to place
your voice when you talk to someone.

And you vocal posture,
when you talk to your spouse,

can help predict not only if,
but also when you will divorce.

So there is a lot to learn
from listening to voices.

And I believe this has to start
with understanding

that we have more than one voice.

So, I'm going to talk
about three voices that most of us posses,

in a model of what I call the mask.

So when you look at the mask,

what you see is a projection
of a character.

Let's call that your outward voice.

This is also the most classic way
to think about the voice,

it's a way of projecting
yourself in the world.

The mechanism for this projection
is well understood.

Your lungs contract your diaphragm

and that creates a self-sustained
vibration of your vocal fold,

that creates a sound.

And then the way you open and close
the cavities in you mouth,

your vocal tract is going to
transform the sound.

So everyone has the same mechanism.

But voices are quite unique.

It's because very subtle differences
in size, physiology, in hormone levels

are going to make very subtle
differences in your outward voice.

And your brain is very good

at picking up those subtle differences
from other people's outward voices.

In our lab, we are working
on teaching machines

to understand those subtle differences.

And we use deep learning to create
a real-time speaker identification system

to help raise awareness
on the use of the shared vocal space --

so who talks and who never
talks during meetings --

to increase group intelligence.

And one of the difficulties with that
is that your voice is also not static.

We already said that it changes
with every person you talk to

but it also changes generally
throughout your life.

At the beginning
and at the end of the journey,

male and female voices are very similar.

It's very hard to distinguish

the voice of a very your girl
from the voice of a very young boy.

But in between, your voice
becomes a marker of your fluid identity.

Generally, for male voices
there's a big change at puberty.

And then for female voices,

there is a change at each pregnancy
and a big change at menopause.

So all of that is the voice
other people hear when you talk.

So why is it that we're so
unfamiliar with it?

Why is it that it's not
the voice that we hear?

So, let's think about it.

When you wear a mask,
you actually don't see the mask.

And when you try to observe it,
what you will see is inside of the mask.

And that's your inward voice.

So to understand why it's different,

let's try to understand the mechanism
of perception of this inward voice.

Because your body has many ways
of filtering it differently

from the outward voice.

So to perceive this voice,
it first has to travel to your ears.

And your outward voice
travels through the air

while your inward voice
travels through your bones.

This is called bone conduction.

Because of this, your inward voice
is going to sound in a lower register

and also more musically harmonical
than your outward voice.

Once it travels there,
it has to access your inner ear.

And there's this other mechanism
taking place here.

It's a mechanical filter,

it's a little partition
that comes and protects your inner ear

each time you produce a sound.

So it also reduces what you hear.

And then there is a third filter,
it's a biological filter.

Your cochlea -- it's a part of your
inner ear that processes the sound --

is made out of living cells.

And those living cells
are going to trigger differently

according to how often
they hear the sound.

It's a habituation effect.

So because of this,

as your voice is the sound
you hear the most in your life,

you actually hear it less
than other sounds.

Finally, we have a fourth filter.

It's a neurological filter.

Neurologists found out recently

that when you open your mouth
to create a sound,

your own auditory cortex shuts down.

So you hear your voice

but your brain actually never listens
to the sound of your voice.

Well, evolutionarily
that might make sense,

because we know cognitively
what we are going to sound like

so maybe we don't need
to spend energy analyzing the signal.

And this is called a corollary discharge

and it happens for every motion
that your body does.

The exact definition
of a corollary discharge

is a copy of a motor command
that is sent by the brain.

This copy doesn't create any motion itself

but instead is sent
to other regions of the brain

to inform them of the impending motion.

And for the voice, this corollary
discharge also has a different name.

It is your inner voice.

So let's recapitulate.

We have the mask, the outward voice,

the inside of the mask, your inward voice,

and then you have your inner voice.

And I like to see this one
as the puppeteer

that holds the strings
of the whole system.

Your inner voice is

the one you hear
when you read a text silently,

when you rehearse
for an important conversation.

Sometimes is hard to turn it off,

it's really hard to look at the text
written in your native language,

without having this inner voice read it.

It's also the voice
that refuse to stop singing

the stupid song you have in your head.

(Laughter)

And for some people
it's actually impossible to control it.

And that's the case
of schizophrenic patients,

who have auditory hallucinations.

Who can't distinguish at all
between voices coming from inside

and outside their head.

So in our lab, we are also
working on small devices

to help those people
make those distinctions

and know if a voice
is internal or external.

You can also think about the inner voice
as the voice that speaks in your dream.

This inner voice can take many forms.

And in your dreams, you actually unleash
the potential of this inner voice.

That's another work
we are doing in our lab:

trying to access
this inner voice in dreams.

So even if you can't always control it,

the inner voice --
you can always engage with it

through dialogue, through inner dialogues.

And you can even see this inner voice

as the missing link
between thought and actions.

So I hope I've left you
with a better appreciation,

a new appreciation of all of your voices

and the role it plays
inside and outside of you --

as your voice is a very critical
determinant of what makes you humans

and of how you interact with the world.

Thank you.

(Applause)