A total of 45 patients were included in the study, whereby data from 43 patients were included in the final analysis (as two patients did not attend the second visit).
Baseline characteristics.
Baseline characteristics are shown in Table 1.
Table 1
| All patients (N = 43) | 432 Hz – 443 Hz (n = 22) | 443 Hz – 432 Hz (n = 21) |
Sex, female (%) | 35 (81) | 16 (73) | 19 (91) |
Age, years | 61 (35–86) | 59 (35–86) | 62 (37–80) |
BMI (kg/m2) | 24 (17–38) | 24 (17–37) | 25 (19–38) |
Married, yes (%) | 23 (54) | 12 (55) | 11 (52) |
Children, yes (%) | 35 (81) | 17 (77) | 18 (86) |
Regular physical activity (%) | 16 (37) | 9 (41) | 7 (33) |
Hearing loss (%) | 0 (0) | - | - |
Preferred music genre (%) (multiple responses possible) | | | |
| Pop | 22 (51) | 12 (55) | 10 (48) |
| Rock | 19 (44) | 8 (36) | 11 (52) |
| Jazz | 14 (33) | 4 (18) | 10 (48) |
| Classical music | 22 (51) | 10 (46) | 12 (57) |
| Hits | 11 (26) | 7 (32) | 4 (19) |
| Hip Hop | 2 (4.7) | 1 (4.5) | 1 (4.8) |
| Others | 13 (20) | 8 (36) | 5 (24) |
QLQ-C30, median (range) |
Global health status | 67 (0–100) | 67 (0–100) | 67 (25–88) |
Functional scales | | | |
| physical | 73 (33–100) | 73 (33–100) | 73 (53–100) |
| role | 67 (0–100) | 67 (0–100) | 67 (0–100) |
| cognitive | 67 (17–100) | 67 (17–100) | 67 (33–100) |
| emotional | 58 (17–100) | 58 (17–100) | 67 (17–100) |
| social | 67 (0–100) | 67 (0–100) | 67 (0–100) |
Symptom scales | | | |
| fatigue | 44 (0–100) | 44 (0–100) | 33 (11–89) |
| pain | 33 (0–83) | 33 (0–83) | 33 (0–83) |
| nausea/ vomiting | 0 (0–100) | 0 (0–50) | 0 (0–100) |
Dyspnoea | 33 (0–100) | 33 (0–100) | 33 (0–100) |
Insomnia | 50 (0–100) | 67 (0–100) | 33 (0–100) |
Appetite loss | 0 (0–100) | 0 (0–67) | 0 (0–100) |
Constipation | 0 (0–100) | 0 (0–100) | 0 (0–100) |
Diarrhoea | 0 (0–100) | 0 (0–100) | 0 (0–100) |
Financial difficulties | 0 (0–100) | 0 (0–100) | 0 (0–100) |
STAI, median (range) | 44 (27–60) | 48 (28–55) | 43 (27–60) |
Data are presented as median (range) or numbers (frequencies). |
BMI, body mass index; QLQ-C30, European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ) composed of 30 questions; STAI, state trait anxiety inventory |
A total of 8 patients were male (19%) and 35 patients (81%) were female. The median age was 61 years (range, 35–86 years). 23 patients (54%) were married and 35 patients (81%) reported having children. Regular physical activity was practiced by 16 study participants (37%).
Most common preferred music genres were pop (22 pts, 51%) and classical music (22 pts, 51%), followed by rock (19 pts, 44%) and jazz (14 pts, 33%).
Median values for global health status, assessed using the QLQ-C30, were 66.7 points (0–100), with median values of 58 to 73 observed for the functional scales and symptom scales ranging from a median of 0 to 50. Median STAI scores, to reflect anxiety levels, were 44 (27–60), and thus slightly above the average for the German population (19).
Cardiovascular parameters.
Cardiovascular parameters were assessed using the VascAssist before (pre) and after (post) the sound intervention (Table 2).
Table 2
Cardiovascular parameters
| 432 Hz (n = 43) | 443 Hz (n = 43) | p-value (Wilcoxon signed-rank test) |
Heart rate (bpm) |
pre | 71 (51–94) | 69 (47–109) | 0.59 |
post | 67 (50–90) | 68 (51–100) | 0.32 |
Difference post - pre | -3 (-15–4) | -1 (-12–9) | 0.04 |
p-value | < 0.001 | 0.01 | |
Brachial systolic BP (mmHg) |
pre | 127 (103–166) | 125 (97–162) | 0.98 |
post | 120 (92–158) | 123 (95–158) | 0.46 |
Difference post - pre | -4 (-25–10) | -3 (-23–5) | 0.48 |
p-value | < 0.001 | < 0.001 | |
Brachial diastolic BP (mmHg) |
pre | 71 (52–92) | 70 (48–91) | 0.69 |
post | 66 (49–89) | 68 (44–91) | 0.12 |
Difference post - pre | -3 (-23–9) | 0 (-15–25) | 0.08 |
p-value | 0.001 | 0.37 | |
RMSSD (ms) |
pre | 21 (7–192) | 24 (6–175) | 0.52 |
post | 27 (9–163) | 25 (6–173) | 0.21 |
Difference post - pre | 3 (-29–42) | 1 (-48–31) | 0.17 |
p-value | 0.01 | 0.40 | |
Resistance (%) | | | |
pre | 63 (15–114) | 56 (14–124) | 0.96 |
post | 54 (15–120) | 55 (21–124) | 0.28 |
Difference post - pre | -5 (-38–18) | -3 (-21–37) | 0.18 |
p-value | 0.008 | 0.29 | |
Stiffness (%) | | | |
pre | 60 (25–101) | 58 (21–95) | 0.52 |
post | 49 (15–91) | 59 (15–95) | 0.04 |
Difference post - pre | -5 (-28–23) | -2 (-29–24) | 0.49 |
p-value | 0.04 | 0.21 | |
Aortic systolic BP (mmHg) |
pre | 106 (87–153) | 109 (83–155) | 0.86 |
post | 105 (81–149) | 110 (80–149) | 0.55 |
Difference post - pre | -4 (-22–6) | -3 (-25–7) | 0.65 |
p-value | < 0.001 | 0.002 | |
Aortic diastolic BP (mmHg) |
pre | 72 (54–94) | 72 (50–93) | 0.91 |
post | 66 (52–91) | 70 (46–92) | 0.09 |
Difference post - pre | -3 (-22–9) | -1 (-14–12) | 0.07 |
p-value | < 0.001 | 0.10 | |
Aix@75 (%) | | | |
pre | 16 (-10–84) | 16 (-16–92) | 0.52 |
post | 15 (-8–92) | 16 (-14–43) | 0.92 |
Difference post - pre | -0.8 (-20–9) | 0.4 (-10–6) | 0.64 |
p-value | 0.68 | 0.85 | |
Aortic PWV (m/s) | | | |
pre | 9 (6–15) | 8 (4–18) | 0.003 |
post | 8 (6–16) | 8 (4–19) | 0.29 |
Difference post - pre | -0.5 (-5–7) | 0 (-15–11) | < 0.001 |
p-value | < 0.001 | 0.70 | |
LVET (ms) | | | |
pre | 270 (207–335) | 267 (199–344) | 0.99 |
post | 272 (227–350) | 271 (193–322) | 0.49 |
Difference post - pre | 6 (-32–62) | 4 (-30–62) | 0.19 |
p-value | < 0.001 | 0.06 | |
Vascular age | | | |
pre | 61 (28–89) | 60 (33–94) | 0.77 |
post | 57 (25–92) | 56 (31–95) | 0.25 |
Difference post - pre | -3 (-16–12) | -1 (-8–17) | 0.11 |
p-value | 0.002 | 0.20 | |
Data are presented as median (range). |
Aix@75, augmentation index standardized to a heart rate of 75 bpm (beats per minute); BP, blood pressure; LVET, left ventricular ejection time; PWV, pulse wave velocity; RMSSD, root mean square of successive difference. |
Vitals
Both interventions led to a significant reduction in heart rate (432 Hz p < 0.001; 443 Hz p = 0.01), with a more pronounced effect for 432 Hz (median reduction − 3 bpm (432 Hz) vs median reduction − 1 bpm (443 Hz), p = 0.04) (Fig. 1a). Systolic blood pressure was also reduced by both interventions (p < 0.001), while diastolic blood pressure did not change. HRV, on the other hand, measured as RMSSD (ms) was increased exclusively by 432 Hz (median increase + 3 ms, p = 0.01; 432 Hz vs 443: p = 0.17) (Fig. 1b).
Vascular indices
The 432 Hz intervention exerted effects on vascular indices, which were not observed at 443 Hz. Both resistance (median reduction − 5%, p = 0.008; 432 Hz vs 443 Hz: p = 0.18) and stiffness (median reduction %, p = 0.04; 432 Hz vs 443 Hz: p = 0.49) were significantly reduced by 432 Hz, with a median decrease of 3 years in vascular age (pre median 61 years (28–89) vs post median 57 years (25–92), p = 0.002; 432 Hz vs 443 Hz: p = 0.11) (Fig. 2).
Central hemodynamics
Effects on aortic blood pressure after the interventions were also detected. While both interventions led to a reduction in systolic aortic blood pressure (432 Hz median reduction − 4 mmHg p < 0.001; 443 Hz median reduction − 3 mmHg, p = 0.002; 432 Hz vs 443 Hz: p = 0.65), changes in diastolic aortic blood pressure were only observed for 432 Hz (median reduction − 3 mmHg, p < 0.001), with a trend towards a statistical difference compared to 443 Hz (p = 0.07). Aix remained unaffected. PWV was significantly reduced by 432 Hz (median reduction − 0.5 m/s, p < 0.001), which was also significantly different compared to 443 Hz (p < 0.001). However, it should be noted that the PWV in the 432 Hz group was significantly higher at baseline than in the 443 Hz group (PWV (m/s) 432 Hz median 9 (6–15) vs 443 Hz median 8 (4–18), p = 0.003). LVET, as indicator of systolic length, was extended by both interventions (432 Hz median increase + 6 ms, p < 0.001, 443 Hz median increase + 4 ms, p = 0.06), but failed to reach statistical significance for 443 Hz.
Psychological outcomes.
An improvement in psychological outcomes was observed in almost all study participants for both sound interventions. This was particularly evident in an increase in emotional well-being (p < 0.001 for both interventions). In addition, both interventions led to a reduction in fatigue, with a more pronounced effect for 432 Hz (432 Hz p = 0.005; 443 Hz p = 0.01). Furthermore, an improvement in anxiety and stress was also achieved in a large number of study participants (VAS anxiety 432 Hz p = 0.008, 443 Hz p < 0.001; VAS stress p < 0.001 for both interventions), although the majority showed no increased VAS scores even before the intervention (median values 0 for anxiety and stress). No statistical difference was found between the effects of the two groups (Table 3).
Table 3
| 432 Hz (n = 43) | 443 Hz (n = 43) | p-value (Wilcoxon signed-rank test) |
VAS Emotional well-being |
pre | 69 (20–100) | 71 (26–100) | 0.83 |
post | 78 (35–100) | 75 (15–100) | 0.64 |
Difference post - pre | 6 (0–50) | 3 (-37–31) | 0.55 |
p-value | < 0.001 | < 0.001 | |
VAS Anxiety |
pre | 0 (0–76) | 0 (0–75) | 0.22 |
post | 0 (0–6) | 0 (0–60) | 0.006 |
Difference post - pre | 0 (-76–0) | 0 (-75–0) | 0.64 |
p-value | 0.008 | < 0.001 | |
VAS Stress |
pre | 0 (0–79) | 0 (0–85) | 0.66 |
post | 0 (0–77) | 0 (0–100) | 0.99 |
Difference post - pre | 0 (-47–0) | 0 (-61–15) | 0.42 |
p-value | < 0.001 | < 0.001 | |
VAS Fatigue |
pre | 13 (0–100) | 28 (0–100) | 0.16 |
post | 0 (0–98) | 2 (0–73) | 0.07 |
Difference post - pre | 0 (-84–18) | 0 (-92–45) | 0.97 |
p-value | 0.005 | 0.01 | |
Data are presented as median (range). |
STAI: state trait anxiety inventory; VAS: visual analogue scale |
Personal assessment.
Twenty-eight patients (65%) reported having noticed a difference between the two interventions. 24 patients (56%) preferred the 432 Hz sound intervention while six patients (14%) appreciated the 443 Hz sound intervention. Almost a third of patients (13 patients, 30%) stated that they liked both interventions equally.