Jj is for Jottings 148.  Other Effects of Noise.

Most of us know about the effects of noise on our hearing, discussed in the previous post.  Spending much time in noisy environments can cause long-term damage to your hearing.  Examples are working in a noisy factory or living near an airport.  Exposure to loud music has the same effect (and you usually have more control over that one).

EXCESSIVE NOISE AFFECTS MORE THAN HEARING.

But we have another body part that is susceptible to damage from noise – the brain.  Before we talk about how the damage can occur, let’s just establish a little more about noise pollution.  A generally accepted definition of noise pollution is “the disturbing or excessive noise that may harm the activity or balance of human or animal life.”  Occasional noise isn’t a problem, but living or working in environments where you’re exposed to constant noise, day and night, can cause health problems that extend beyond hearing loss.

Hearing loss can, however, result from a single loud sound (like firecrackers) near your ear. Or, more often, hearing loss can result over time from damage caused by repeated exposures to loud sounds. The louder the sound, the shorter the amount of time it takes for hearing loss to occur. The longer the exposure, the greater the risk for hearing loss (especially when we don’t use hearing protection or there is not enough time for the ears to rest between exposures).

TWO TYPES OF DAMAGE.

Two types of damage occur during and after you are exposed to loud sounds. Loud sounds destroy many of the sensory hair cells in your ears.  These are the cells that send that send neural messages.  After that, your inner ear fills up with fluid that leads to the death of neurons.

The build-up of fluid pressure in the inner ear is something you might notice if you go to a loud concert.  When you leave the concert, your ears might feel full and you might have ringing in your ears. This fluid build-up correlates with neuron loss.  Once those neurons die, there’s no treatment that can replace them at this stage.

Lab tests at the University of Texas show that severe hearing loss stops a large number of neurons in the auditory cortex from working.   These traumatised cells go dormant and no longer respond to sound at all. And those which are not put out of action may behave in slow motion, sending signals more slowly and with less accuracy.  Less stimulation in any area of the brain leads to fewer connections and reduced function.  This is the downside of neuroplasticity in action.

Moderate hearing loss, thankfully, doesn’t destroy any neurons, but it does lengthen the time they need to respond to sound, according to this study. And the neurons are less sensitive, requiring louder sounds to provoke a reaction.

COGNITIVE ABILITIES.

All of these neuronal changes affect your cognitive abilities. As a result, it is more difficult to engage in conversation and complicates your attempts to communicate. The person with hearing loss may utilise several types of nonlistening – pseudo-listening, selective listening, and even monopolising.  If you monopolise a conversation you cut out the time you have to devote to listening.  And that equates to less time feeling vulnerable and out of control.  We can truly say that hearing loss, from any cause, poses a major obstacle to good listening as well as to cognition.

All these effects can lead to social isolation, which can make people more vulnerable to Alzheimer’s disease or other cognitive problems.

It is clear that the effects of loud noise on the brain are inextricably linked to hearing loss, but there are other effects of loud noise.

OTHER PHYSIOLOGICAL EFFECTS.

A study published in the British Medical Bulletin found that noise interferes in complex task performance, modifies social behaviour and causes annoyance. I’m sure we’ve all observed those things anyway, either in ourselves or in others.  I certainly find that I have a low tolerance to noise.  I find it difficult to concentrate and it is extremely irritating.  And annoyance and irritation may lead to stress, which can lower the body’s resistance to illness and disease.  There are heaps and heaps of current, good quality studies linking stress with illness and disease.  And with inflammation, which also underlies many diseases.

Stress-related hormones which the adrenal glands secrete prepare the body for “fight or flight” by increasing blood pressure and heart rate and releasing glucose (sugar) into the body to be burned for energy.  This can cause psychological stress and restrict blood flow to the heart and brain, increasing the risk of heart attack and stroke.  If no fighting or fleeing occurs, all these things still happen without the accompanying activity to properly utilise them, and that’s where the real problem lies.

According to this study, occupational and environmental noise exposure may also be associated with high blood pressure.  This is in addition to the elevated levels of stress hormones which the adrenal glands secrete.

Taken all round, exposure to loud noise is not at all good for us on many levels, and is something to avoid where possible.  The previous article gives ideas on how to prevent noise from affecting us.

COUNTERACTING THE EFFECTS OF NOISE.

In addition to preventing exposure to loud noise, there are some steps you can take to counteract some of the negative physiological effects – although not the hearing loss.  Research shows that spending time in quiet green spaces, whether it’s a city park or a rural setting outside the city, can reduce cortisol levels, lower blood pressure, reduce heart rate and generally provide measurable stress relief.  A person’s blood pressure can plummet just by spending 20 minutes in such a place.  And don’t forget the similar effects from stroking our pets.

It’s worth taking a moment to think about the noise levels in our everyday lives. Given that we now know there are numerous negative effects, we need to take steps to reduce exposure where possible.  Where this isn’t possible, we can counteract the effects of noise exposure.

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