How Hearing Works

Summary

This script delves into the marvel of human hearing, explaining how sound vibrations are transformed into neural signals by the ear's intricate structure. It highlights the crucial role of hair cells in the cochlea and the irreversible consequences of their loss, such as severe hearing loss or deafness. The video also touches on the impact of age-related hearing loss, known as presbycusis, and the importance of protecting our ears from loud noises to preserve our auditory abilities.

Takeaways

• 👂 Hearing involves the detection of vibrations in air or water that stimulate our ears, resulting from the collaboration between the ear and the brain.
• 🧠 The auditory process includes reflex responses, perception at the auditory cortex, and voluntary responses involving other brain areas.
• 🔍 The ear is divided into three parts: external, middle, and inner, with the cochlea in the inner ear being crucial for sound vibration transformation.
• 🌐 Sound waves travel from the external ear, through the ear canal, causing the eardrum to vibrate, which is then transmitted to the cochlea by the ossicular chain.
• 🌟 Hair cells in the cochlea are essential for converting sound vibrations into neural signals, with the organ of Corti housing these sensory cells.
• 🚨 There are approximately 15,000 hair cells in the cochlea, which do not regenerate, making them critical for maintaining our hearing ability.
• 🎶 Normal hair cells allow us to discriminate frequencies of sound, contributing to our ability to perceive pitch and musical scales.
• 📉 Degeneration of hair cells, particularly outer hair cells, can lead to severe hearing loss and a significant loss of pitch discrimination.
• 🔊 Exposure to loud sounds can cause irreversible damage to hair cells, resulting in deafness and tinnitus, emphasizing the importance of hearing protection.
• 👴 Presbycusis is age-related hearing loss that mainly affects high pitches and can be accelerated by exposure to loud noises.
• 📢 The decibel scale categorizes sound levels, with prolonged exposure to sounds above 90 decibels posing a risk to hearing health.
• 🛡️ To preserve hearing, it's important to minimize exposure to loud noises in both work and leisure environments.

Q & A

How do we perceive sounds?

We perceive sounds through vibrations that spread in air or water and stimulate our ears. The process involves the collaboration between the ear and the auditory brain, with the external ear capturing vibrations that cause the eardrum to move, the middle ear amplifying the sound, and the inner ear transforming these vibrations into neural signals sent to the brain.

What is the role of the auditory brain in hearing?

The auditory brain is crucial for the perception of sound. It processes the neural signals received from the ears, allowing us to recognize and interpret sounds. Without the ears, the brain cannot process sound, and without the brain, we cannot perceive what sound is like.

What happens to our hearing when we are asleep?

While asleep, our ears and auditory pathways continue to function, and reflexes can still occur. However, other brain regions involved in emotions, motivations, memory, etc., are inactive, leading to no voluntary responses or conscious perception of sound.

How is the eardrum connected to the inner ear?

The eardrum is mechanically linked to the inner ear by the ossicular chain, which transmits the vibrations of the eardrum to the liquid within the cochlea of the inner ear.

What is the function of the cochlea in the inner ear?

The cochlea is a spiral-shaped structure in the inner ear where sound waves are transformed into neural signals by the organ of Corti, which contains sensory hair cells.

Why are hair cells in the cochlea important for hearing?

Hair cells in the cochlea are vital because they translate sound vibrations into neural signals. They are sensitive to the bending caused by sound vibrations, which triggers the creation of neural signals that are sent to the brain for interpretation.

How many hair cells does the cochlea contain, and can they regenerate?

The cochlea contains approximately 15,000 hair cells, and these cells do not regenerate. Damage or loss of hair cells can lead to hearing loss.

What happens if hair cells degenerate?

If hair cells degenerate, it can result in hearing loss and a severe loss of pitch discrimination, affecting language intelligibility. Complete loss of hair cells leads to total deafness.

What is presbycusis and how does it affect hearing?

Presbycusis is a progressive hearing loss that occurs with age, mainly affecting high pitches. If it affects speech frequencies, it can become a significant handicap, potentially starting at an earlier age due to factors like exposure to loud noises.

How can exposure to high sound levels impact our hearing?

Exposure to high sound levels can cause irreversible damage to our hair cells, resulting in deafness and tinnitus. The louder the sound, the less time is needed for damage to occur.

What are some ways to protect our hearing from damage?

To protect our hearing, we should minimize exposure to loud noises at work and during leisure activities. This can help preserve our ability to hear for years to come.

Outlines

00:00

👂 How Our Ears Work and the Importance of Hair Cells

This paragraph delves into the mechanics of hearing, explaining that it's a collaborative process between the ear and the brain. Sound vibrations are captured by the external ear, amplified by the middle ear, and transformed into neural signals in the cochlea of the inner ear. The auditory nerve sends these signals to the brain, where they are processed at various levels to create the perception of sound. The paragraph emphasizes the critical role of hair cells in the cochlea, which, if damaged or lost, can lead to hearing loss and a diminished ability to discern pitch and language. It also touches on the phenomenon of presbycusis, a form of age-related hearing loss, and the impact of loud noise exposure on hearing health.

05:00

🚫 The Risks of Noise-Induced Hearing Loss

The second paragraph focuses on the dangers of exposure to high sound levels, which can cause irreversible damage to hair cells and lead to deafness and tinnitus. It illustrates how excessive noise can gradually harm and eventually kill hair cells, resulting in a loss of hearing ability. The paragraph advocates for minimizing exposure to loud noises in both work and leisure environments to preserve one's hearing for the long term. It concludes with a call to action, directing viewers to the Hearing Health Foundation and Cochlea.org for more information on hearing protection and awareness.

Keywords

💡Hearing

Hearing is the process by which the brain interprets sound vibrations that travel through the air or water and stimulate our ears. In the video's context, hearing is the result of a collaboration between the ear and the auditory brain, emphasizing that without ears, one cannot even imagine what sound is like. The script also highlights the importance of the brain's role in processing auditory information.

💡Eardrum

The eardrum, also known as the tympanic membrane, is a thin membrane that separates the outer ear from the middle ear. It plays a crucial role in the hearing process by vibrating in response to sound waves, which then gets amplified and transmitted to the inner ear. The script mentions the eardrum's mechanical linkage to the ossicular chain, which further transfers these vibrations.

💡Cochlea

The cochlea is a spiral-shaped, fluid-filled structure in the inner ear that is responsible for converting sound vibrations into neural signals. The script describes how sound waves reach the eardrum and cause it to vibrate, which in turn sets the fluid in the cochlea into motion, stimulating the hair cells within.

💡Hair Cells

Hair cells are sensory receptors found in the inner ear, specifically within the organ of Corti in the cochlea. They are essential for translating sound vibrations into electrical signals that can be interpreted by the brain. The script emphasizes the importance of hair cells, noting that they do not regenerate and their loss can lead to hearing loss and a diminished ability to perceive pitch.

💡Auditory Cortex

The auditory cortex is a region of the brain where sound is perceived. It is part of the process of hearing that involves not just the physical reception of sound but also the cognitive interpretation of those sounds. The script explains that the auditory cortex works in conjunction with other brain areas to create conscious perception and recognition of sounds.

💡Presbycusis

Presbycusis is a form of age-related hearing loss that affects high-frequency sounds and can eventually impact speech frequencies. The script mentions that presbycusis is a progressive condition that may be accelerated by exposure to loud noises, potentially leading to early onset of hearing difficulties.

💡Decibels

Decibels are a unit of measurement used to express the intensity of sound. The script uses decibels to classify the potential risk to hearing from different sound levels in the environment, noting that exposure to sounds above 90 decibels can lead to irreversible damage to hair cells and resultant hearing loss.

💡Tinnitus

Tinnitus is a condition characterized by a ringing or buzzing in the ears, often as a result of damage to the hair cells in the cochlea. The script mentions tinnitus as a possible consequence of exposure to high sound levels that can cause irreversible damage to the hair cells.

💡Ossicular Chain

The ossicular chain is a series of three small bones in the middle ear—the malleus, incus, and stapes—that mechanically link the eardrum to another membrane closing the inner ear. The script describes how the vibrations of the eardrum are transmitted through the ossicular chain to the cochlea, amplifying the sound vibrations.

💡Organ of Corti

The organ of Corti is a structure within the cochlea that contains the sensory hair cells. It is where the actual transduction of sound vibrations into neural signals occurs. The script provides a detailed description of the organ of Corti and its role in the hearing process.

💡Sound Vibrations

Sound vibrations refer to the oscillations in air or other mediums that are produced by sound sources and stimulate the ear. The script explains that these vibrations are the initial step in the hearing process, starting with the external ear capturing them and causing the eardrum to vibrate.

Highlights

Hearing involves the collaboration between the ear and the auditory brain, emphasizing the importance of both components for the perception of sound.

The ear is composed of three parts: the external, middle, and inner ear, each playing a crucial role in the process of hearing.

Sound waves are captured by the external ear and transmitted through the eardrum and middle ear to the cochlea in the inner ear.

The cochlea contains hair cells that are vital for translating sound vibrations into neural signals.

Hair cells in the cochlea are responsible for sound discrimination and are irreplaceable once lost.

The organ of Corti, located in the cochlea, contains sensory hair cells that connect with the auditory nerve.

The process of hearing involves three different brain levels, including reflex, auditory cortex, and other areas for conscious perception.

During sleep, the ears and auditory pathways remain active, but voluntary responses and conscious perception are inactive.

Presbycusis is a form of progressive hearing loss with age, primarily affecting high pitches and potentially speech frequencies.

Loud noise exposure can accelerate presbycusis, leading to early onset of hearing handicap.

Exposure to high sound levels can cause irreversible damage to hair cells, resulting in deafness and tinnitus.

The decibel scale classifies sound levels in the environment and indicates the risk of hearing damage.

Up to 80 decibels, there is no risk to the ear regardless of sound exposure duration.

From 80 to 90 decibels, the risk of hearing damage is limited to very long exposures.

Above 90 decibels, the danger zone for hearing damage is entered, with damage occurring more quickly as sound levels increase.

Minimizing exposure to loud noises can help preserve hearing ability for years to come.

Resources for more information on hearing health are available at hearing health foundation org and cochlea org.

Transcripts

what do here what is hearing how do our

ears work and why are hair cells so

important and what happens if we lose

them we hear sounds vibrations that

spread an air or water and stimulate our

ears

hearing is the result of the

collaboration between the ear and the

auditory brain and ear without a brain

is like an unplugged microphone but

without ears we would not even be able

to imagine what a sound was like once

captured by our external ear the

vibrations caused the movement of the

eardrum sound is amplified by the middle

ear and transfer to the inner ear or

cochlea which transforms the sound

vibrations into a neural signal the

auditory nerve feeds this coded message

which contains all the sounds attributes

to the brain where different structures

work together to create the perception I

can hear when awake the process of

hearing involves three different brain

levels a reflex level where the arrival

of a message may cause us to jump or

turn our head the auditory cortex where

the sound is perceived and other brain

areas which allow the perception to

become conscious recognize the sound by

comparing it to those that have

previously been memorized and determine

an appropriate voluntary response when

asleep our ears and auditory pathways

are still working and reflexes can still

occur but the other brain regions

involved emotions motivations memory etc

are inactive they are therefore no

voluntary responses or conscious

perception the ear is composed of three

parts the external middle and inner ear

the ear canal is closed off by the

tympanic membrane or eardrum in the

middle ear the eardrum is mechanically

linked by the ossicular chain to another

membrane which closes the inner ear the

hearing part of the inner ear is rolled

up into a spiral called the cochlea

sound waves are caught by the external

ear and pass tell me ear canal until we

reach the eardrum and make it vibrate

the ocular chain then mechanically

transmitted the vibrations to the liquid

of the cochlea

Kolia are hair cells which translate

sound vibrations into neural signals by

zooming in on the transverse section of

the cochlea we can see the organ of

Corti which contains the sensory hair

cells and one single hair cell in its

connection with the auditory nerve after

the sound has been translated by the

hair cell neural signals are sent to the

brain through the auditory nerve why our

hair cells so important providing that

they have developed normally our cochlea

only contains 15,000 hair cells and

these cells do not regenerate we can

clearly see the hair cells they are

being bent under sound vibrations which

cause the hair cells to become excited

and create a neural signal providing

that the sound transmission is not

altered and the brain works normally our

hearing is fine in normal hair cells we

can perfectly discriminate the

frequencies of sound of a musical scale

what happens when a hair cells

degenerate in this image outer hair

cells the more fragile type have

degenerated however inner hair cells are

still there this corresponds to a severe

hearing loss and moreover a severe loss

of pitch discrimination language

intelligibility is strongly altered

without the outer hair cells we can hear

some background sound but barely

distinguish the musical scale listen

in this image all hair cells have

disappeared

this of course results in total deafness

presbycusis is a progressive hearing

loss with age this type of hearing loss

concerns mainly high pitches when it

affects the speech frequencies it

becomes a handicap usually by the age of

80 or 90 presbycusis may be accelerated

by injury such as loud noise exposures

therefore the handicap may start at a

much earlier age which may result in

having at forty a 90 year old cochlea

this cell level

in decibels classifies the sound in our

environment into four categories up to

80 decibels there is no risk for the ear

regardless of the duration of the sound

exposure from 80 to 90 decibels we are

getting closer to the danger zone but

the risks are limited to very long

exposures

above 90 decibels is the danger zone the

louder the sound the less time is needed

for damage to occur

exposure to high sound levels can cause

irreversible damage to our hair cells

resulting in deafness and tinnitus this

animation represents the habit caused by

to loud sound on one of our sensory

cells at about 90 decibels the hairs may

be gradually damaged and eventually the

hair cell finally dies if too many hair

cells die we lose our capacity to hear

by minimizing overexpose

to loud noises at work and during

leisure activities you'll be able to

enjoy your hearings for years to come

for more information go to hearing

health foundation org and cochlea org

you