How Does Loud Noises Cause Hearing Loss?

Approximately 3.6 million Australians are currently living with some level of hearing loss. Unfortunately, more than one in three of these people have a form of noise-related ear damage or other hearing condition that could have been prevented.^[1] With hearing being such an instrumental part of our daily lives, this begs the question: how does loud noise lead to hearing loss - and are the things we’re doing daily putting us at risk?

Recap: How We’re Able To Hear

To understand how exposure to loud sounds can cause damage that leads to hearing loss, we need to understand how we can hear sounds in the first place. Here’s a little recap of how sound moves through the three distinct parts of our ear - the outer, middle and inner ear.

First, sound waves from our environment (everything from talking to cars driving by or planes in the sky) enter our outer ear and travel through a narrow passageway called the ear canal, which leads to our eardrum.
When these sound waves hit the eardrum, they set it in motion. The eardrum is a paper-thin membrane that vibrates when sound waves hit it, similar to a drum.
The eardrum sends vibrations to three tiny bones in the middle ear, which also move.
The movements from these bones transmit sound waves into the inner ear and the cochlea, a snail shell-shaped organ filled with a fluid that moves in response to the vibrations.
These fluid movements and vibrations are then transformed into electrical impulses by cells known as hair cells as they bend. We have approximately 16,000 hair cells; unfortunately, they cannot heal or regrow once damaged.
The electrical signals produced by the hair cells travel along the auditory nerve to our brain.
Finally, our brain processes and decodes these signals, turning them into meaningful sounds, like speech, a phone ringing, or a smoke alarm, which we hear clearly.

1. Loud Sounds Can Damage The Inner Ear

Now that we’ve covered how our body turns sound waves into that we can hear, the first way that loud noises can lead to hearing loss is by damaging or destroying the hair cells within our inner ear, which cannot be regenerated or repaired.

Specifically, prolonged or repeated exposure to loud sounds above safety thresholds can cause the hair cells to bend too far or too frequently, exceeding their ecstatic limits. This results in their damage, which may occur in one of two ways:

• The hair cells may endure a temporary threshold shift, in which you will experience a temporary reduction in hearing sensitivity (temporary hearing loss, like after a concert) that will resolve after some time and rest. If this occurs, your hair cells have been stressed but not permanently damaged.

• The hair cells suffer permanent damage or even death. Both cases mean you permanently lose those hair cells, which impairs your ability to detect and transmit sound signals effectively. Depending on the extent and location of the hair cell damage, different frequencies and volumes of sounds may be affected, resulting in various degrees of hearing loss.

In Australia, the safety threshold for sound is 85 decibels over 8 hours at work (the level of blenders, lawnmowers and leaf blowers).[2] If you’re being exposed to loud noises for a shorter timeframe, i.e., 2 hours, the acceptable decibel range may be slightly higher - for this 2-hour example; it can be raised to 91 decibels. You must take great care to not expose your ears to a noise level above 140 decibels without ear protection that will lessen the noise. Any exposure above this 140-decibel level could instantly damage hearing. Sledgehammering or gunshots can be 140 decibels or higher.

There is also a one-metre rule that you can follow to help ensure safe noise levels: if you need to raise your voice to talk to someone who is standing or sitting one metre away, and this is the constant level of noise throughout the day, then the level of noise is probably too high.

2. Loud Sounds Can Produce Reactive Oxygen Species (ROS)

Exposure to excessively loud sounds can also lead to the production of reactive oxygen species (ROS), which are highly reactive molecules that cause oxidative stress and damage to the delicate structures of the inner ear.

Specifically, the excessive energy associated with loud noise exposure can disrupt the normal balance of reactive oxygen species and antioxidant defences, leading to oxidative stress. Once the reactive oxygen species are produced in the inner ear, they can disrupt the biochemical processes essential for the hair cells' functioning and contribute to their degeneration.

This is where minimising your exposure to loud sounds and employing hearing protection strategies, such as earplugs or earmuffs, can help reduce the generation of reactive oxygen species and mitigate the risk of oxidative stress-induced hearing loss.

3. Loud Sounds Can Damage The Auditory Nerve Fibres

Auditory nerve fibres are crucial for transmitting electrical signals from the inner ear to the brain, so we can interpret and understand the sounds we hear. Exposure to loud noises above the safety thresholds can damage the auditory nerve fibres, contributing to hearing loss. The result includes:

• A reduction in the quality and clarity of sound perception, meaning sounds become more muffled and unclear
• Hearing loss at softer volumes, making it more difficult to hear quieter sounds and maintain conversations
• Greater difficulty understanding speech in noisy environments, as the ability to distinguish between different speech sounds may be compromised
• Greater difficulty determining the direction that sounds are coming from, as well as perceiving timing cues in sound

Signs That Your Noise Exposure May Be Damaging Your Hearing

Your hearing may be at risk if, after your exposure to the noise, you’re noticing:

• Ringing or buzzing in your ears
• Temporary hearing changes - like greater difficulty hearing others
• Pain in your ears
• Sensitivity to loud sounds
• Difficulty understanding speech
• Feelings of fullness or pressure in the ears
• Fatigue or tiredness after the exposure, as excessive noise can be both physically and mentally exhausting

Limiting Your Exposure To Excessive Noise

In most cases, it cannot be reversed once the noise-related damage is done. Hence, it’s very important to protect your ears and hearing when you know you will be in loud environments. We recommend:

• Using hearing protection devices: earplugs or earmuffs can significantly reduce the intensity of loud sounds and safeguard the ears from damage. They are essential in noisy environments such as concerts, construction sites, or industrial settings.

• Reducing your exposure to loud sounds: minimising the duration of your exposure to loud sounds whenever possible can help protect your hearing. If working in noisy environments, aim to take breaks in quieter areas to allow the ears to rest and recover.

• Controlling volume where possible: when using personal audio devices, keep the volume at a moderate level and limit the duration of headphone use. Consider noise-canceling headphones to reduce the need for high volume levels.

• Screen your workplace: when taking on a new job in an industry that involves regular repeat exposure to loud noises, ask about what engineering controls have been implemented, such as sound insulation, that work to reduce noise levels in workplaces or public spaces actively.

Suppose you’re concerned that you may have experienced some ear damage or hearing loss. In that case, it’s time to book an appointment with our ear care professionals, who will examine your ears, make an accurate diagnosis, rule out any underlying conditions, and get started on an appropriate treatment plan to prevent further hearing loss and minimise the impact it has on your life.

Book an appointment with our friendly team at your local centre here.

^[1] https://www.health.gov.au/topics/ear-health/about

^[2] https://www.safeworkaustralia.gov.au/safety-topic/hazards/noise/overview