The effect of noise on the neonatal unit and on neonatal transfer

Deafness Research UK is supporting a study led by Dr Lesley Jackson at the Glasgow Royal Infirmary to assess the risk to newborn babies of hearing loss after exposure to noise during neonatal care.

[Equipment grant: 2006-2008]

Neonates that have been admitted to intensive care are 10.2 times more likely to have a sensorineural hearing loss (“nerve” deafness) or mixed hearing loss (combining sensorineural and conductive hearing loss) than those who are not.

As noise-induced hearing loss is a well recognised phenomenon, the project aims to addresses excessive noise in both the neonatal unit and on inter-hospital transfers.

Infants are transferred between hospitals by the Neonatal Transport Team for many reasons. These are often very sick or premature babies who are transferred by ambulance, plane or helicopter as required. Noise levels during transfers have been reported as high as 99 DbA, although the recommendations for noise levels on neonatal intensive care units themselves are set at 45-50 DbA.

In the first part of the study the team measured noise levels both inside and outside transport incubators in 30 transfers by a mix of ambulance, plane and helicopter. To asses the effect of noise on the inner ear, he team have made recordings from the neonates of a particular type of otoacoustic emission (the noise that healthy ears emit). These emissions show changes after noise induced hearing loss.

Initial results showed no hearing loss for the babies but did find high levels of noise across some of the ambulance worker’s shifts. The research team are now investigating the noise levels staff are exposed to and are measuring the noise on the neonatal units.

Data from the study will be able to inform any new recommendations for safe levels of noise for both neonates and NHS workers.