Immediate Effects of a Headphone-Delivered Natural Soundscape on Agitation and Physiological Parameters in Intensive Care Unit Patients: A Randomized Clinical Trial

Abstract

Background: The acoustic environment of an intensive care unit (ICU) can contribute to patient distress and agitation. Continuous sound delivered through headphones may reduce exposure to abrupt ward noise; however, different sound types should not be considered acoustically equivalent. Objectives: To compare the immediate effects of a 30-minute headphone-delivered natural soundscape with those of routine ICU care on agitation and selected physiological variables. Methods: In this parallel randomized clinical trial, 76 adults admitted to the ICUs of Shohadaye Tajrish Hospital in Tehran, Iran, were assigned in a 1:1 ratio using variable-block randomization. The intervention consisted of a 30-minute composite recording of ocean waves, rainfall, and running water delivered through headphones between 4:00 and 5:00 p.m.; it was not acoustically verified as white noise. The Richmond Agitation-Sedation Scale (RASS), assessed immediately after the study period, was designated as the primary outcome. Heart rate, systolic and diastolic blood pressure, mean arterial pressure, and peripheral oxygen saturation (SpO2) were exploratory secondary outcomes. Seventy participants (35 per group) had post-assessment data and were included in the complete-case analysis. Results: The mean post-assessment RASS was -0.91 ± 1.64 in the natural-soundscape group and -0.03 ± 0.85 in the routine-care group. The unadjusted mean difference was -0.88 (95% CI, -1.50 to -0.26; P < 0.001). The mean heart rate was also lower after the study period in the intervention group (mean difference, -8.03 beats/min; 95% CI, -9.93 to -6.13; P < 0.001). Post-assessment systolic blood pressure, diastolic blood pressure, and mean arterial pressure did not differ between the groups. SpO2 was lower in the intervention group at baseline and remained lower after the study period (post-assessment mean difference, -2.52 percentage points; 95% CI, -4.12 to -0.92; P = 0.003). Conclusions: In an exploratory complete-case analysis, the full headphone-delivered natural soundscape intervention was associated with lower post-assessment RASS scores and heart rate than routine care. The study design cannot disentangle the effects of the recording from those of headphone use, attenuation of ward noise, or additional researcher contact. Baseline-adjusted intention-to-treat analyses using participant-level data are required before efficacy can be concluded.