Witt, Catherine L.
Originally published in the June 2008 issue of Advances in Neonatal Care
This month we have several articles that focus on developmental care. One in particular addresses the issue of noise in the neonatal intensive care unit (NICU). As the authors point out, noise continues to be a problem in many NICUs, despite well-documented evidence that excessive noise can cause permanent damage to the hearing of neonates.1–3
This knowledge has been available for a long time. In 1974, even before the advent of NICUs, the US Environmental Protection Agency recommended that hospitals maintain a sound level of no more than 55 dB during waking hours and 45 dB during sleeping hours.4 Despite these recommendations, noise levels in the NICU have been recorded as high as 90 to 140 dB.1–3 Alarms and equipment account for some of the noise. Conversations with coworkers, radios, and other activities make a significant contribution to overall noise levels.
This is bad not only for neonates but also for staff. Prolonged exposure to noise levels louder than 80 dB is considered potentially dangerous. Both hair cells of the inner ear and the auditory nerve can be damaged by prolonged or repeated exposure to noise. Scientists once believed that the pure force of vibrations from loud sounds caused the damage to hair cells. Instead, recent studies have shown that exposure to harmful noise triggers the formation of molecules inside the ear that can damage or kill hair cells. First, high-frequency hearing loss occurs. Loss of high-frequency hearing distorts sounds that are necessary for understanding speech. When hearing impairment begins, the high frequencies are often lost first, which is why people with hearing loss often have difficulty hearing the high-pitched voices of women and children.
Both the amount of noise and the length of exposure to the noise influence the amount of damage to our hearing.5 The National Institute on Deafness and Other Communication Diseases estimates that 10% of people aged 20 to 69 years (more than 22 million people) have suffered permanent hearing damage.6
Hearing loss is not the only health hazard of repeated exposure to excessive noise. Noise has been shown to increase blood pressure and breathing rate, increase levels of circulating cortisol, interfere with digestion, and potentiate the effects of some drugs, alcohol, and carbon monoxide.5,6 It increases fatigue and causes irritability and interferes in performance of routine daily tasks. It can interfere with attention to detail, which increases the risk of accidents and errors in job situations. The Occupation Safety and Health Administration has mandated that noise be monitored and workers be provided with hearing protection if exposed to noise levels exceeding 85 dB.7 Noise makes communication with coworkers and families more difficult. Increased levels of concentration and energy are required to listen and hear, and to speak above the noise. As a result, voices can be strained and vocal cords are abused. It is physically and mentally stressful to carry on even an enjoyable conversation in the presence of noise.5,6
If we know this information, why do we repeatedly expose ourselves to loud noises and allow the decibel levels in our work environment to exceed what is good for our neonates and us? Could it be that we have become immune to noise pollution in our everyday environments? Recently a news organization in Portland Oregon used hidden cameras and sound-level meters to measure decibel levels at popular retail establishments in the Portland area.8 They repeatedly found levels of noise to be at 90 dB or higher, particularly at clothing stores and other retailers targeting teenagers. The report explained that some of these retailers have policies mandating that music be played at levels of 80 to 85 dB. The belief is that the music increases excitement and leads to increased purchases.8 While shopping with my daughter at a popular clothing store that caters to teenagers, we were having difficulty conversing, not because of a mother–daughter issue, but because the music volume was so loud that we could not hear one another talking in a normal voice. Eventually, much to my daughter's dismay, I asked the clerk whether the volume could be lowered. He informed me that the volume was mandated by corporate policy and they were not allowed to adjust it. We become desensitized to the volume levels, or we do not notice them because we have already begun to lose hearing.
The increase in cortisol levels, blood pressure, and breathing rates reported with loud noise creates a feeling of excitement and well-being. Many people report that listening to loud music makes them feel good, creates a sense of euphoria, and makes the music more enjoyable. I once complained at my church about the volume of music at a service that morning and was told that they wanted to get people excited! We might be excited, but we could all be deaf as well!
Everyday noise pollution includes city traffic (85 dB), motorcycles (120–150 dB), and rock concerts (140 dB). We have headsets, household appliances, food processors, and noisy toys. We spend time in malls, restaurants, stadiums, churches, and countless other places where noise levels exceed what is safe. With all this exposure to excess noise, is it any wonder that we do not notice excessive noise levels in the NICU?
What can we do to protect our hearing and that of our patients? We first need to recognize excessive noise when it is happening. We do not need a decibel meter to know what is too loud. Normal conversation is about 60 dB. If we have to raise our voices to be heard, we are being exposed to toxic levels of sound. Multiple conversations, radios, equipment, and alarms almost certainly contribute to a toxic environment in the NICU.
To protect yourself, consider hearing protection when exposed to loud noises in the community (heavy traffic, rock concerts, mowing the lawn, or riding a snowmobile). Hearing protection such as ear plugs can reduce noise exposure by as much as 25 dB.5,6 Limit your length of exposure to loud noise. Turn down the volume on the radio or on your headphones. Your mother was right—if others can hear music from your headset when standing 3 feet away, it is too loud.5,6
Educate yourself and others about the dangers of excess noise. As nurses, we have a responsibility not only to our patients but to the public health as well. Do not be afraid to ask others to turn down the volume. Be an advocate for reducing noise pollution. Your county may have a local noise ordinance. Find out what you can do in your community to advocate for quiet. For example, some schools have set a decibel limit for the music played at school dances to protect students' hearing. Remember there are no regulations governing how loud sound can be in public places such as discos, movie theaters, dance clubs, exercise centers. Work with owners, managers, and community leaders to create a healthier less noxious listening environment.
Be aware of the noise in your environment and take control of it when you can. Think about noise when buying appliances, recreational equipment, and children's toys. Choose quieter models when available.
Remember that changing the noise levels in our NICUs benefits not only our patients but also ourselves. Some units have instituted quite periods in their NICUs. Consider implementing such times in your work environment. Avoid unnecessary conversation and other noise. You might find it relaxing for you and for your patients.
1. Kreuger C, Wall S, Parker L, Nealis R. Elevated sound levels within a busy NICU. Neonatal Network
2. Willimas A, van Drongelen W, Lasky R. Noise in contemporary neonatal intensive care. J Acoust Soc Am
3. Walsh W, McCullough K, White R. Room for improvement: nurses' perceptions of providing care in a single room newborn intensive care setting. Adv Neonatal Care
4. Environmental Protection Agency, Office of Noise Abatement and Control. Information on levels of environmental noise requisite to protect public health and welfare with an adequate margin of safety. 1974. http://www.epa.gov/history/topics/noise/01.html.
Accessed March 15, 2008. Washington, DC: Government Printing Office.