NeoSTRESS: Study of Transfer and Retrieval EnvironmentalStressorSupon neonates via a smartphone application - Sound

Aim This study aimed to measure sound exposure during neonatal retrieval, determine whether this varied with mode of transport, and compare noise exposure to recommended levels in neonatal intensive care units. We also aimed to assess the acceptability of using a smartphone application to measure sound. Setting: Neonatal retrieval service in Brisbane, Australia. Methods The Physics Toolbox Sensor Suite application was installed on a Samsung Galaxy S5 smartphone and calibrated for sound measurement. Data were collected during outbound, non-patient legs of 45 retrievals - 25 road, 11 fixed wing aircraft and 9 rotary aircraft journeys. Data were saved to cloud storage, then analysed using PostgreSQL database. Results The median sound level was 83 dB (interquartile range 66-91; range 27->= 97 dB). Continuous equivalent sound (L-eq) was 90 dB across all journeys. Rotary transport was loudest (L(eq)94 dB). Fixed wing (L(eq)89 dB) and road (L(eq)87 dB) journeys also resulted in significant sound exposure. Sound exceeded recommended levels (45 dB) for 99% of all journey time, regardless of the mode of transport. Conclusions Neonates encounter harmful sound levels during retrieval - louder than recommended levels for 99% of all retrieval time. Sounds levels were highest in rotary aircraft transport compared to fixed wing or road transport. It is feasible to use a calibrated smartphone application instead of a sound metre.