Fig. 3From: The responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact sound: a pilot studySound pressure level (SPL) of floor impact sounds (FIS) with or without soundproof mattress. Abbreviation: B, bang machine; T, tapping machine; I, impact ball; BT, B and T; TI. T and I; BI, B and I; M, soundproof mattressBack to article page