Maud Hulsman-Dohmen carefully pulls up the bunny by one of its ears. The fluffy stuffed animal – named Pip – that normally sits on the corner of her desk, gets to sit on her lap for now. Over four years ago, Pip embarked on an adventure to explore the world of children, Hulsman-Dohmen explains with a laugh. For her doctoral research in the Building Acoustics research group, she studied the impact of sound on the child’s brain, from newborns to young adults.

The youngest participants in her field studies got to work with Pip, about whom Hulsman-Dohmen had written a short book. “For a week, we monitored children’s daily activities and the sounds around them. Pip was curious about all the sounds they heard and helped them fill out a diary. Pip tagged along with the children on outings, and thanks to the GPS tracker in Pip’s backpack, we were able to record their activity patterns.”

Distraction

“Children’s physical and mental health is increasingly under pressure,” Hulsman-Dohmen begins. “But at the same time, we still know very little about the exact influence of all sorts of environmental factors. We do know that, along with to second-hand smoke and air quality, noise plays a significant role in the development of health problems.” Sounds do not only influence your body, Hulsman-Dohmen stresses.

“Another misconception is that noise is only harmful if, for example, it wakes you up. Even softer noise, from about 33 dB, can prevent you from entering into a deep sleep. Your brain remains active in the background.” In addition, noise also causes distraction, she continues. “We know from previous studies that children who grow up in an environment with a lot of traffic noise fall behind in their mental development by as much as three months.”

These studies on the impact of noise on health focus on either the physical or the social environment. Within the EU project ‘Equal-Life,’ in which TU/e and Avans University of Applied Sciences also participate, Hulsman-Dohmen works in a completely different way. There, the “exposome” is the central focus – a unique approach. “We approached the child’s living environment with a different mindset. All the environmental factors you’re exposed to during your life are what we call the exposome. This can be divided into an internal part, which includes your metabolism, hormones and inflammatory responses, and an external part.”

This covers the physical (indoor and outdoor) and social environments (social stressors, lifestyle). “Together, they influence your health, in both positive and negative ways. For example, noise exposure is not only likely to be unevenly distributed across different socio-economic conditions, but social factors can also make you more susceptible to stressors, which may cause you to react differently to noise. It’s an amalgamation of sensitivities – and in this study, we’re trying to discover connections.”

Couch potatoes during COVID

But just when Hulsman-Dohmen has handed out the first diaries and GPS trackers to her participants, the COVID-19 pandemic breaks out. The Netherlands is faced with lockdowns, social distancing and a society that is largely shut down. Panic sets in for Hulsman-Dohmen, who sees her carefully designed research go up in smoke. However, her participants continue collecting data even during the COVID-19 era, and it is precisely these data that now provide a scientific glimpse into child behavior during the pandemic.

“Based on their activity behavior, we were able to divide the children into four groups. The outdoor players, the socially active explorers, the hoppers – who exhibited traits from all categories – and the ‘social homebodies,’ the couch potatoes, if you will. In the latter group, we mostly saw participants within the 12-17 and 18-21 age groups, with significantly increased screen time. At the same time, the percentage of mental illness – which had been stable for years – suddenly spiked. The teen group was heavily restricted during the pandemic; they couldn’t go to school and they were no longer allowed to play sports in groups or get together.”

“The impact of that social isolation continues to this day; a warning to the government. Hopefully, they will learn from studies like this and take this insight into account during any future epidemics. When drafting restrictive measures, they should consider young people, because they are particularly vulnerable – especially at a stage in life when they’re discovering themselves socially.”

Less perseverance

In a comprehensive statistical study following the pandemic, Hulsman-Dohmen tried to establish relationships between various variables – she lists: “age, gender, education level, living environment, how pleasant/safe/green the living environment is, social contacts, I could go on and on” – and also: how noise is experienced. “We see that children who are frequently exposed to noise increasingly exhibit a form of learned helplessness. A chronic sense of lacking control over the situation, which can also reduce initiative-taking behavior. That can be very damaging to mental health.”

“We further investigated that mechanism by having children solve puzzles. Using a pencil, they were to trace line drawings without lifting the tip off the paper or retracing their own lines. Two of the figures were impossible to solve. Children with a cognitively fatigued brain – from having completed math problems beforehand – approached the puzzle differently. We observed that the children exposed to elevated noise levels in their environment showed significantly less perseverance; they gave up much more quickly. An alarming finding.”

The groups of children who participated in Hulsman-Dohmen’s studies are too small to draw any concrete conclusions. However, the results do demonstrate how complex the impact of noise on health is, especially in children who are developing on all fronts. “A great first step towards looking at environmental factors in a new, much broader way.” And Pip? The bunny has been given a role as a mascot, and observant attendees may even spot him somewhere behind the lectern during Hulsman-Dohmen’s dissertation defense.