Effects of natural environmental sounds on cognition of peculiar noises in hospital ward

This study attempted to examine the effects of natural environmental sounds on human cognition of peculiar noises to explore the methods for improving the sound environments in hospital wards. Since the natural environmental sounds used in our previous study reduced uncomfortableness of some noises in hospital wards, we expected a similar effect of natural sounds on peculiar noises. Participants were 25 female and 15 male college students. Four peculiar noises characteristics to hospital wards (nurse call, sucking, footsteps, and ambulance siren) and ten natural sounds constituting a typical natural sound environment in Japan [sounds of stream, water-filled bamboo tube striking a stone, Japanese Tit (Parus minor), Japanese Bush Warbler (Horornis diphone), Large Brown Cicada (Graptopsaltria nigrofuscata), Higurashi Cicada (Tanna japonensis), Cricket (Teleogryllus emma), Bell-ringing Cricket (Homoeogryllus japonicus), iron wind bell, and glass wind bell] were presented both separately and in combination. The participants were asked to evaluate the degrees of annoyance and uncomfortableness created by hearing them. They rated the separate noises, not so much annoying but somewhat uncomfortable while they rated both the annoyance and uncomfortableness of the natural sounds low. However, combining the peculiar noises with the natural sounds did not lower the ratings of uncomfortableness of the peculiar noises although our previous study showed that it could reduce the uncomfortableness of noises produced by provision of daily patient care in hospital wards. This seems to be attributable to the difference that the noises in the present study convey some messages arousing some sort of anxiety while those in the previous study had no specific message. Therefore, to improve the subjective sound environment of the hospital wards, nurses should provide their patients with information preventing anxiety caused by the peculiar noises in an early stage of admission.