I used to joke about my kids having selective hearing when they were little. Call them to do the dishes and they didn’t hear me. But whisper the word, “dessert,”  and suddenly they’d appear in the kitchen with hopeful smiles.

Until recently, I didn’t realize how important true selective hearing is to our well-being. Technically known as Selective Auditory Attention, it enables us to block out unnecessary noise so we don’t get overwhelmed by sounds. But there’s one group of people in the world who don’t have selective hearing. For them, noise isn’t just a nuisance but is dangerous to their health and even their survival.

Premature Babies “Hear” the World Differently

I stumbled on this fact as I was learning about a recent project completed using SoundPly’s acoustic ceiling planks in a critical space—the Neonatal Intensive Care Unit (NICU) of Nemours/duPont Children’s Hospital. I was curious. Did our acoustic planks live up to the hospital’s description of “whisper quiet?” There was only one way to find out. I called the hospital and asked to speak with Amanda Bloomfield, a NICU nurse practitioner.

Bloomfield’s candor and passion for her work was refreshing. She was new to Nemours NICU and noticed a big contrast when she started working there. “It was quieter. I didn’t know what made the difference but I could tell it was quieter than when I practiced at the other hospital in town.” She then went on to explain why “whisper quiet” is such a big deal for premature babies. “Noise levels make a huge difference. When it’s noisy, infants are burning more calories because of stress; and they’re not growing as well.”

I took notes as she shared about the impact of noise on premature babies. Why would noise impact premature babies so severely? I learned it’s because premature babies actually hear the world differently than we do, due to their immature nervous systems. This is where Selective Auditory Attention comes in.

Selective hearing isn’t possible for preterm infants. Without a mature nervous system, they can’t block out or “get used to” noise. Without the ability to filter noise, even a quiet environment can have many hostile sounds. These sounds – machines, voices, cabinets closing – startle them each time they’re heard. This results in a measurable stress response. 

Noise causes stress and limits growth

Studies show noises in the NICU directly affect a premature infant’s vital signs. They increase a baby’s heart rate, O2 saturation, respiratory rate, blood pressure, and intracranial pressure.

Like Bloomfield shared, these indicators of stress negatively impact a premature baby’s ability to grow, heal, and thrive.

In addition, high noise levels may also damage a premature baby’s hearing. According to the American Academy of Pediatrics, noise in the NICU often exceeds the recommended maximum 45 decibels (dB). To put it in context, a whisper is about 20-30 dBa while a quiet home environment is 40 dBa. A normal conversation is about 60 dBa.

But in the NICU, noise levels may intermittently be as high as 100 dB from simply closing the solid plastic portholes on the baby’s incubator. One study showed ventilator tubes may produce sound pressure levels of 60-115 decibels when in contact with an infant’s facial bones.

A Goal of “Whisper Quiet”

With the well-being of children at stake, reducing noise in the NICU was a top priority for the award-winning Nemours/duPont Children’s Hospital in Wilmington, DE. Their goal? Create a calm, nurturing space for the smallest and most vulnerable patients; a NICU where preterm infants can thrive.

Architects from Ewing Cole knew NICU rooms needed to become “whisper quiet” but  they had to overcome some challenges to get there. For example, hospitals require cleanable floors and walls but these hard surfaces amplify and reverberate sound waves. Reverberation also increases the Lombard Effect –  the tendency of speakers to talk louder when they’re in a noisy environment. The Lombard Effect can be difficult to reduce unless the environment changes.

To alter the noise levels within the NICU, an acoustic treatment needs to absorb sound waves rather than reflect them. The acoustic product selected also needed to be:

• Antimicrobial
• Cleanable
• Class A fire-rated
• Lightweight
• Capable of suspension from ceiling grids
• Have excellent sound absorption
• Require no additional acoustic backing or fabric
• Have a warm, inviting appearance

The Acoustic Solution

Exceptional acoustic performance was needed, one with a guarantee to work. It was a tall order, but SoundPly’s Lino Acoustic Planks by Navy Island fit the bill. To absorb sound, Lino Planks use micro perforations on the surface of the veneer. These tiny holes absorb sound waves into the plank’s engineered core, rather than reflect them from the plank’s surface. Navy Island calls its patented micro-perforation technique, MicoPerfection® technology. It absorbs significantly more sound than similar products while meeting the hospital’s other needs, as well.

Today the thoughtfully designed NICU and nurturing staff create a quiet, healing environment for the littlest VIPs at Nemours Children’s Hospital. It’s a hush described as “whisper quiet,” brought by a product known as SoundPly, so the tiniest babies have the greatest chance at a healthy future.

In a NICU environment, it’s imperative for designers to consult an acoustician. An acoustician can independently test acoustics in an environment to be sure they are performing at desirable levels.