Sir, I read with interest a recent publication in the BDJ entitled 'The sound of dentistry'. 1 Researchers at the NIOSH, in collaboration with EA LAB, have developed the NIOSH Sound Level Meter App.2

This app is available for any iOS device and integrates the best features from noise dosimeters and professional quality sound level meters into a simplified tool.2 The purpose of the app is to enable people to conduct workplace noise testing, prevent hearing loss due to occupational factors and ensure informed decision-making on noise exposure.2

The app has been developed by hearing loss experts and acoustics engineers, is freely available for downloads, is validated and tested, gives accurate measurements, provides the user with relevant metrics similar to the ones available in professional sound instruments, has screens with information on conducting measurements, hazardous levels of noise, guidelines on hearing loss as well as selection of appropriate hearing protectors.2 The app is also enabled to connect with NIOSH hearing experts for technical assistance.2

The data can be shared and reported, and the app is also capable of calibrating both an external and internal microphone.2 It encompasses numerous metrics important for proper measurements of noise in an occupational setting in accordance with the OSHA and NIOSH standards (90 dBA permissible exposure limit and 85 decibels recommended exposure limits for an eight-hour average respectively).2

Professional quality sound level meters are mandated to comply with a number of international and national standards. The NIOSH SLM app meets the IEC 61672:3 standard when used with a calibrated external microphone.2 It can be utilised to create awareness in workers and as a research tool.