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

Abstract

病棟で発生する騒音に対する自然環境音の効果を調べた．被験者は大学生40名であった．音刺激は， 4種類の病棟で聞こえる特徴的な騒音と10種類の自然環境音を用いた．被験者は，各騒音及び各自然環境音の他， 騒音と自然環境音を組み合わせた音を提示され，うるささと不快さの程度の評価を求められた．その結果，各騒音に対して，うるささは特に強くは感じられないが，ある程度不快に感じることが示された．自然環境音に関しては，うるささは感じられず，不快さも高くはなかった．しかし，騒音と自然環境音を同時に提示した時には， 不快さの程度は騒音のみを提示した場合と同程度に高かった．本研究では，病棟で起こる騒音による不快感の低減に対して，自然環境音は効果的には作用しない場合があることが示唆された．これについては，本研究で使用した騒音が何らかの望ましくない状況や身体状態を意味する音であったという違いに帰因すると考えられた．This study attempted to examine the effects of natural environmental sounds on human cognition of noises to explore the methods for improving the sound environments in hospital wards. Since the natural environmental sounds used in a 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 environmental sound 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 environmental 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 undesirable conditions while those in the previous study had no specific message. Therefore, to improve the subjective sound environment of the hospital wards, staffs should provide their patients with information about noises in an early stage of admission.departmental bulletin pape