It’s well understood how loud noise can affect your hearing – instantly, or in years to come.

What’s emerging is a better understanding of how noise can affect your life in many other ways, from putting you at risk for heart disease and other illnesses to lowering your child’s ability to learn in school.

Mathias Basner, an associate professor of sleep and chronobiology at the University of Pennsylvania School of Medicine, began studying the effects of noise when he was a research associate in the flight physiology division of the German Aerospace Center and was looking into how aircraft noise interfered with sleep.

His interest grew from there. He now is involved in sleep research, noise research, and, oddly enough, astronaut behavioral health. He explains: “Short sleep and noise are problems in space flight as well. The International Space Station is very noisy.”

Mathias Basner is an associate professor of sleep and chronobiology at the University of Pennsylvania School of Medicine.
Penn Medicine
Mathias Basner is an associate professor of sleep and chronobiology at the University of Pennsylvania School of Medicine.

Basner recently spoke to us about noise and health.

What, exactly, is noise?

Noise is defined as unwanted sound. So it has both a physical component and a psychological component. My boilerplate example for that is a rock concert. Recently, I was at [a concert by the K-pop boy band BTS] with my daughter, and I measured the sound level at 105 decibels. Actually, my typical example is someone being exposed to 100 decibels at a rock concert, and I always wondered if it was too high. Evidently, it’s not. Luckily, we used earplugs to protect ourselves. But there were a lot of people who didn’t do that, and they likely caused permanent damage to their hearing. If the concert had been a workplace, everyone would have been required to wear hearing protection by law.

Anyway, in this typical example, even if the music is very loud, most people don’t think of that as noise because they like the band, they have paid a lot of money for the tickets, and they’re enjoying this greatly. But for someone living three blocks away from the concert hall, trying to read a book or go to sleep, the sound level is much lower, yet that person still thinks of the music as noise. That is the psychological component, the circumstance that makes the sound unwanted. People feel annoyed, which induces a stress reaction that can have health consequences in the long run.

So while noise-induced hearing loss is predominantly, if not completely, determined by the sound energy — the sound-pressure level — and how long you are exposed, for many of the other noise-related health effects the circumstances matter in addition to the sound level.

Beyond damage to our hearing, you’ve said even minor noise disturbs sleep. How?

Obviously, we know that high-quality sleep of sufficient length is super important for us. It recuperates us, affecting our long-term health and well-being. Anything that disturbs sleep can have negative health consequences.

The auditory system has a very specific role. It serves a watchman function because it’s constantly monitoring our environment, especially when we’re sleeping. From an evolutionary perspective, sleep is a dangerous period. Entering a state where we are unconscious and unaware of our surroundings makes us easy prey. So there has to be a channel that is still monitoring the environment. If we hear a lion roaring, that would be a good signal to wake up.

This is why the auditory system is so important during sleep, but also prone to induce sleep disturbance. Noise intruding into our bedroom can cause us to wake up during the night. It can prevent our blood pressure from going down and disturb important regenerative processes that occur during sleep. For example, what we learn during the day is consolidated during sleep, and we flush out metabolic toxic products during sleep that accumulate in the brain while we are awake.

The problem is that we are often not aware of what the noise is doing to our sleep. If we monitor the sleep of people with electrodes, we can see that the brain clearly switches from the sleep state to the wake state. But these awakenings are often too short for us to regain waking consciousness. So we are unaware of a lot of these noise-induced awakenings. If we are unaware of a problem, we are unlikely to do something about it.

In what other ways does noise harm us?

Noise obviously disturbs communication. Everyone has been in a loud restaurant trying to hold a conversation. Sometimes, it’s not even possible. What people will do to cope is raise their voices. Sometimes you have to pause the conversation — as when an aircraft is flying overhead. It’s also more likely to be misunderstood in a noisy environment. That’s likely why studies have shown that the students who attend school in noisy areas lag behind academically relative to those who attend schools in quiet areas. The teacher is saying something, the student doesn’t understand it correctly, and it just goes from there.

Another very important non-auditory effect is an increase for the risk of cardiovascular disease — high blood pressure, a higher rate of heart attacks, potentially a higher rate of stroke. The idea is that whenever we are exposed to noise — unwanted sound — the body excretes stress hormones like adrenaline and cortisol that change the composition of our blood and affect blood vessels. Noise can be especially stressful if we have no control over it, if we feel at the mercy of someone else.

The noise-induced risk increases for these diseases are not dramatic relative to other risk factors, like smoking. But so many people are exposed to relevant levels of noise. That makes it a major public health problem.

Cardiovascular disease is the one that is best understood. But researchers are starting to look at other diseases, including diabetes, cancer, and obesity, that might be linked to noise exposure as well.

How do you know if you’re being exposed to too much noise? When is loud too loud?

If it bothers you, it meets the criteria for the definition of noise. Once you start changing your behavior, it’s too much noise. You might not even be aware that you’re doing it, but if you reflect, you might realize you’re avoiding outside areas, increasing the volume of your TV, raising your voice. Some people move their bedroom into the basement. Some people move to a new home -- although, obviously, not everyone can afford that. Noise can affect the value of your home. A quiet area is an attractive area to move into. Noisy areas are often less expensive and attract people with lower income, who have little political influence. In that sense we have a noise equity problem.

What can people do to lessen their exposure to noise?

Actually, moving your bedroom is not a bad idea. In the case of road traffic, often there is an exposed facade of the house facing the road. And there is a back side where noise levels are usually much lower.

In general, noise should be a priority when you’re picking where you live. I suggest visiting the property during different times of the day. Often, the real estate agent will take you there on a weekend. There’s no noise. But then you go on a weekday, and there’s all this noise from traffic. Make noise a priority. You may be living in the new place for 10 to 20 years, and you want to enjoy it and not suffer the health consequences.

Obviously, I do not want to downgrade the auditory effects. That’s a huge problem. We need to raise awareness that too much noise can damage your hearing. If it’s too loud, you need to speak up. For instance, demand that the manager of the movie theater where the sound is too loud to turn it down. If that doesn’t work, get away from the noise. Ask for your money back and leave. It’s not worth it for a movie that lasts for two hours to damage your hearing for the rest of your life. Also, always take hearing protection to a concert.

Noise-canceling headphones are a great invention. I use them all the time on planes. They reduce the background level of sound, and we adjust the volume of what we’re listening to relative to this background level. This helps lower the sound energy you are exposed to.