Abstract
Objective:
This study aimed to investigate the effects of binaural beat technology (BBT) sound stimulation therapy on the physiological and psychological functioning of elderly patients with coronary heart disease (CHD) following percutaneous coronary intervention (PCI).
Methods:
This study is a retrospective cohort study. Clinical data of 104 patients with CHD undergoing PCI from January 2022 to December 2024 were retrospectively analysed. The patients were grouped according to the time of introduction of the hospital’s postoperative therapy plan into the conventional group (n = 53, patients receiving standard therapy between January 2022 and May 2023) and the BBT group (n = 51, patients receiving standard therapy plus BBT therapy between June 2023 and December 2024). Comparisons included physiological indices (diastolic blood pressure [DBP], systolic blood pressure [SBP], heart rate [HR]; sleep quality (Richards–Campbell Sleep Questionnaire [RCSQ] score, polysomnography [PSG] parameters [slow-wave sleep duration, total sleep time, nocturnal awakenings]; perceived stress (10-item Perceived Stress Scale [PSS-10]; mood states (Brief Profile of Mood States [BPOMS] and psychological distress (Hospital Anxiety and Depression Scale [HADS] anxiety subscore, depression subscore and total score).
Results:
One week after the operation, the BBT group had lower levels of DBP, SBP, HR, PSS-10 score, BPOMS score, HADS anxiety, depression dimension scores and total HADS score; higher RCSQ score; longer deep sleep time and total sleep time and fewer night awakenings than the conventional group (P < 0.05).
Conclusion:
BBT sound stimulation therapy improves haemodynamic stability, enhances sleep architecture, reduces perceived stress, ameliorates mood disturbances and alleviates psychological distress in elderly patients with CHD post-PCI.
Keywords: coronary heart disease, percutaneous coronary intervention, sleep quality, sound stimulation
KEY MESSAGES:
-
(1)
BBT acoustic stimulation therapy can improve haemodynamics in elderly patients with CHD after PCI.
-
(2)
BBT frequency sound stimulation therapy can improve the perceived stress and psychological stress of elderly patients with CHD after PCI.
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(3)
BBT sound stimulation therapy can improve the sleep quality of elderly patients with CHD after PCI.
INTRODUCTION
Coronary heart disease (CHD) represents a leading cause of disability and mortality among the elderly population worldwide. According to the American Heart Association’s (AHA) 2025 Heart Disease and Stroke Statistics,[1] the 2023 Report on Cardiovascular Health and Diseases in China[2] and the Global Burden of Disease study,[3,4] individuals aged 60 years and above account for 60–70% of the global CHD patient population. In China, CHD prevalence among adults aged ≥60 years constitutes approximately 41.2% of the total cardiovascular disease burden in this demographic. Furthermore, elderly patients exhibit a comparatively high incidence of complications (approximately 20%) within 1 year following percutaneous coronary intervention (PCI), including stent thrombosis and heart failure, which significantly exceeds rates observed in young cohorts. This elevated risk profile, compounded by age-related declines in physiological reserve and a high burden of comorbidities, predisposes elderly patients to post-PCI haemodynamic instability and sleep disturbances, imposing substantial socioeconomic burdens on families and healthcare systems.[5] Research indicates that persistent concerns regarding long-term risks, such as stent thrombosis and myocardial reinfarction, often present as anxiety states characterised by ‘illness uncertainty’ and ‘anticipatory fear of sudden cardiac death’ in elderly post-PCI patients. These psychological responses align with the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition diagnostic criteria for ‘adjustment disorder with anxiety’ and may subsequently disrupt sleep architecture.[6,7] Additionally, diuretic therapy to reduce cardiac preload post-PCI frequently induces nocturia, which disrupts slow-wave sleep. The resulting deterioration in sleep quality can further hinder cardiopulmonary adaptation during recovery, adversely affecting overall postoperative outcomes.[8] Consequently, implementing structured rehabilitation management following PCI is essential to optimise comprehensive patient outcomes and alleviate the associated familial and societal burdens in this vulnerable population.
Current rehabilitation strategies for elderly post-PCI patients are primarily categorised into conventional management and non-pharmacological approaches. Conventional management emphasises physiological parameter monitoring, dietary/activity guidance, basic psychological support and group health education, but it demonstrates limited efficacy. Although rhythmic breathing, white noise, heart rate variability (HRV) biofeedback and progressive muscle relaxation demonstrate documented efficacy, their application in elderly populations presents specific limitations, such as rhythmic breathing requires active respiratory control, which may hinder compliance in the elderly; white noise lacks frequency-specific modulation of sleep-related brainwaves; HRV biofeedback relies on specialised monitoring equipment with substantial cost and operational complexity and progressive muscle relaxation involves physical activity that is inappropriate for bedbound post-PCI patients.[9,10,11,12] Thus, a notable clinical gap persists for easily administered, cost-efficient and precisely targeted non-pharmacological solutions for this demographic.
Binaural beat technology (BBT) is a non-pharmacological approach that delivers dichotic auditory stimuli of slightly different frequencies to each ear. The brain perceives the binaural beat, which may synchronise neural oscillations to facilitate relaxation and alleviate stress. This therapy has been utilised in managing perioperative anxiety (e.g., patients undergoing mandibular wisdom tooth extraction and upper gastrointestinal endoscopy), elderly individuals with poor sleep quality and populations with Alzheimer’s disease.[13,14,15,16] These target groups are primarily middle-aged and older adults without severe hearing impairment, who present with mild-to-moderate anxiety/sleep disturbances and generally tolerate non-pharmacological approaches well. BBT was selected for this study because of its unique neuromodulatory mechanisms, including auditory steady-state response (ASSR) and frequency-following response (FFR), and its suitability for elderly patients. Specifically, BBT relies on ASSR and frequency-specific neural entrainment. When the cochleae receive binaural beats, the brainstem auditory pathway generates symmetric low-frequency phase-locking, inducing cortical theta/alpha wave synchronisation. This process directly inhibits the prefrontal–amygdala stress circuit without requiring active cognitive participation, which is consistent with the cognitive characteristics of elderly patients. Furthermore, compared with white noise, BBT can precisely modulate the sleep–wake cycle via FFR to prolong slow-wave sleep duration. Unlike HRV biofeedback, BBT administration is simple, requiring only noise-cancelling headphones, and nurses can become proficient after a brief 2-hour training session. However, reports on the BBT application in elderly PCI patients are rare, offering limited reference. Notably, age-related hearing loss is common in the elderly and may reduce binaural phase synchrony, potentially weakening the brainstem phase-locking effect of BBT. Therefore, screening for normal auditory function was essential for participant selection. Given this rationale, patients with CHD admitted to our institution over the past 3 years underwent auditory screening to exclude those with compromised cochlear processing ability. Ultimately, clinical data from 104 eligible patients with CHD were analysed to investigate the effects of BBT acoustic stimulation on physiological (blood pressure, heart rate [HR] and sleep) and psychological (perceived stress, mood state and psychological distress) functioning in elderly patients with CHD after PCI, aiming to provide a basis for their postoperative rehabilitation management.
MATERIALS AND METHODS
Patient Characteristics
From January 2022 to December 2024, a total of 108 patients were evaluated for eligibility. Among them, one was excluded because of severe arrhythmia, one was excluded because of a history of depression and two were excluded because of severe renal impairment. Ultimately, 104 patients were included in the final analysis. A retrospective cohort study was conducted to analyse the clinical data of 104 patients with CHD who underwent PCI treatment at the People’s Hospital of Baishan from January 2022 to December 2024. According to the introduction time of the postoperative treatment plan in the hospital, the data of 53 patients who received conventional therapy from January 2022 to May 2023 were included in the conventional group, and the data of 51 patients who received conventional therapy plus BBT sound stimulation therapy from June 2023 to December 2024 were included in the BBT group. The patients and their families were informed of the study content and signed informed consent forms. The study conformed to the ethical principles of the World Medical Association’s Declaration of Helsinki.[17] The study was approved by the Institutional Ethics Committee of People’s Hospital of Baishan (Ethics Review KY2025008). The selection process of research objects is shown in Figure 1.
Figure 1.
Flow chart of subject selection. Note: BBT, binaural beat technology.
Inclusion and Exclusion Criteria
(1) The inclusion criteria were as follows: ① patients met the CHD diagnostic criteria per the European Society of Cardiology and the American College of Cardiology Foundation/AHA guidelines[18,19]; ② patients aged ≥60 years; ③ patients undergoing primary PCI with clinical stability (defined as haemodynamic stability, absence of chest pain, dyspnoea, or severe arrhythmia within 24 hours post-PCI and urine output ≥30 mL/h); ④ patients with complete medical records; ⑤ patients with no history of psychiatric disorders, with preserved cognitive and communicative capacity (defined as a Mini-Mental State Examination score ≥24), and ability to comply with scale assessments (defined as capacity for independent scale completion or clear responses to investigator queries); ⑥ patients with normal auditory function (pure-tone average threshold ≤25 dB HL at 0.5, 1, 2 and 4 kHz) and ⑦ patients with a hospitalisation duration ≥7 days.
(2) The exclusion criteria were as follows: patients with ① significant primary hepatic, renal, or other organ dysfunction; ② severe uni- or bilateral visual/auditory impairment (pure-tone threshold >70 dB HL, or interaural frequency discrimination difference >5 Hz); ③ discontinuation due to mortality or inter-hospital transfer; ④ concurrent critical conditions (e.g., acute myocarditis, aortic dissection, cardiogenic shock, severe arrhythmias) and ⑤ pre-existing diagnosis of anxiety or depressive disorders.
Methods
Conventional Group
Patients in the conventional group received conventional postoperative therapy. The following steps were performed. (1) Monitoring of vital signs and prevention of complications: Changes in vital signs such as HR, blood pressure, blood oxygen saturation and body temperature, as well as blood routine and coagulation function after surgery, were closely monitored. The 24-hour urine output after surgery (report to the doctor immediately if it is less than 30 mL/h) was observed. The patient was asked if they had any discomfort symptoms such as chest pain, chest tightness, palpitations and sweating. The patient was informed to be vigilant for signs of asymptomatic myocardial ischaemia, acute pericardial tamponade, gastrointestinal bleeding (black stool, haematemesis) and gum bleeding. Antiplatelet drugs were used strictly in accordance with the doctor’s orders. The patient and their family were informed of the drug name, dosage, administration time, side effects and risks of missed doses. Medication was not stopped without permission. The family was instructed to participate in supervision together. (2) Therapy of the puncture site: The family members were instructed to keep the puncture site clean. A dedicated compression device was used to apply pressure and bandage the puncture site of the radial artery. The puncture point was observed for bleeding and haematoma at regular intervals (1–2 hours each time). The pressure was gradually reduced based on the coagulation condition 6–8 hours after the operation. The bandage was removed 24 hours later. A sandbag was used to apply pressure on the puncture site of the femoral artery for 6–8 hours. The patient was maintained in a supine position, and the affected limb was immobilised for 24 hours (with the affected lower limb extended). The pulse of the dorsalis pedis artery and the skin temperature of the lower limb were monitored to prevent venous thrombosis. Family members were guided to assist the patient in massaging the surrounding skin at regular intervals. (3) Diet and defecation guidance: 2 hours after the operation, family members were advised to prepare light liquid food for the patient (such as warm water and rice soup), avoiding overeating to mitigate cardiac strain. The regular diet should be low in salt and fat, high in fibre and contain an appropriate amount of high-quality protein. The patients were instructed to avoid raw, cold and spicy foods. For patients with femoral artery puncture, the first defecation after the operation should be done in bed as much as possible to prevent straining. (4) Positioning and activity guidance: For patients undergoing femoral artery puncture, the affected lower limb was maintained in a non-ambulatory status for 10–12 hours. Upon completion of immobilisation, patients were assisted into a semi-Fowler’s position (with the head of the bed elevated at 30°). Caregivers were instructed to perform passive limb massage (10–15 times/hour) to prevent deep vein thrombosis. For patients with radial artery access, the affected upper limb was immobilised for 6–8 hours. After this period, patients were assisted with bedside repositioning and gentle limb movement, followed by sitting with support for meals. Between 12 and 48 hours postoperatively, patients were guided to perform standing exercises at the bedside and slow ambulation within the room with caregiver assistance. From postoperative day 3 to week 1, patients were instructed to walk for 10–15 minutes daily with family support, while avoiding stair climbing and heavy lifting. (5) Sleep disorder management: Appropriate temperature and humidity were maintained in the ward, operations were concentrated, noise was reduced and the use of diuretics before bedtime was avoided. (6) Psychological guidance and social support: Videos, pictures and other forms were used to patiently explain the pathogenesis, development patterns, surgical effects and prognosis of CHD to patients, making them aware of the treatability and controllability of the disease. The importance of standardised postoperative treatment, emotional management and good sleep was emphasised. Family members were encouraged to accompany, understand and comfort patients and face the disease with a positive attitude.
BBT Group
Patients in the BBT group received conventional therapy (the same as the conventional group) plus BBT frequency sound stimulation therapy. (1) BBT sound stimulation type and production: ① Pure tone production: Audio editing software (audacity, version 2.1.0, created by independent software developer Christopher R. Langer from the United States) and frequency generation tools (online signal generators and built-in software sound effects) were used to produce pure tones (i.e., sounds characterised by a single frequency component, with a single frequency and relatively simple timbre). ② Background music selection: According to the characteristics of elderly patients with CHD, simple and soothing background music (ready-made music with complete musical structure, diverse timbres and melodic lines) should be chosen, such as classical music (Mozart’s ‘K.398 Piano Duet’ and Bach’s ‘Goldberg Variations’); natural soundscapes (e.g., river sounds, bird songs, forest sounds, waterfall sounds and ocean sounds) and pure music (e.g., piano, guitar and harp) and ③ BBT sound stimulation production: The pure tones produced by the above audio software were integrated into the background music and edited into binaural beat music with the same duration as the background music (about 30 minutes). During the production programming, synchronous breathing guidance phrases (e.g., ‘Now please breathe along with the sound. Breathe in slowly through your nose, count 1, 2, 3, 4, and let your belly expand. Hold your breath for 1 to 2 seconds, then breathe out through your mouth, count 1, 2, 3, 4, 5, 6, and imagine breathing out the tension. You can also use hand gestures, raise your palm when inhaling and lower it when exhaling’.) were inserted. After production, the file was exported as a stereo WAV or MP3 format and saved in the patients’ mobile phone or tablet, naming it as ‘10 Hz Alpha Wave PCI Postoperative Relaxation Music’ and so on [Figure 2]. (2) Implementation of BBT music therapy: ① Equipment and environment: We selected a pair of over-ear headphones with independent noise cancellation for left and right channels (ear cup diameter ≥ 8 cm, avoiding pressure on the auricular cartilage, model XL-520, Dongguan Xiaolin Electronics Co., Ltd., Dongguan, Guangdong). ② Psychological preparation and pre-adaptation to headphones: Before treatment, the patient was informed that ‘I will be monitoring you throughout the process. If you feel any discomfort, raise your hand to signal’. We explained that the sound during treatment may be like a distant buzzing sound, which would relax the brain and reduce the burden on the heart. The patient was allowed to try on the headphones for 5 minutes, adjusting the tightness and volume of the headphones (the volume should be set so that the patient felt no pain in the ears, and the sound was clear but not harsh). ③ Formal implementation: We assisted the patient to assume a comfortable position (semi-recumbent position [with the head of the bed elevated at 30° and a soft pillow placed under the knees to prevent sliding] or supine position [with the pillow height at the same level as the shoulders to avoid excessive extension of the neck], enter a state of rest and relaxation and helped the patient in wearing headphones to listen to the binaural beat music. The initial duration was 15 minutes per session (if the patient had no discomfort symptoms, it was gradually extended to 30 minutes per session). At the end of the treatment, the volume was reduced to 30 dB and maintained for 30 seconds before turning off the audio. The patient was then informed that the treatment was over, and their headphones were slowly removed. If the patient fell asleep during the treatment, they were not awakened; the lights were turned off, and the remaining time was continued. Frequency adjustment principle: If the patient’s HR decreased by less than 10 beats per minute after treatment, a slightly higher alpha wave range (such as a binaural beat of 12 Hz) was attempted to enhance the stimulation. Time of administration: We started from the second day after surgery, with two treatments per day: one in the afternoon (12:00–13:30) and one before going to bed in the evening (19:30–21:00). During the evening treatment, a 10-minute warm water foot bath was incorporated. Continuous treatment was provided for 1 week [Figure 3]. To evaluate patient compliance, nurses verified the duration of audio playback per treatment session. Participants were considered to have completed the full listening protocol when achieving 80% or higher of the target duration. Compliance rate was calculated as follows: (actual completed listening sessions / planned sessions) × 100%. A compliance rate ≥80% was defined as good compliance. In this study, patients demonstrated excellent cooperation, with an average compliance rate of 99.32%.
Figure 2.
Flowchart of BBT sound stimulus types and production process. Note: BBT, binaural beat technology, CHD, coronary heart disease.
Figure 3.
Flowchart of the implementation process of BBT sound stimulation therapy. Note: BBT is binaural beat technology.
Observation Indicators
(1) Haemodynamic parameters: Diastolic blood pressure (DBP), systolic blood pressure (SBP) and HR were measured at 7:00–8:00 am on postoperative day 1 and week 1 in both groups. (2) Sleep quality assessment: At postoperative day 1 and week 1: ① The Richards–Campbell Sleep Questionnaire (RCSQ), which was developed by Richards et al.[20] and translated into Chinese by Chen et al.,[21] was used to assess the sleep quality of the two groups. The scale comprised five dimensions (a. number of awakenings, b. difficulty falling asleep, c. overall sleep quality, d. difficulty falling back asleep and e. sleep depth). Each dimension was scored using a 0–100 mm visual analogue scale, with 0 at the left end indicating poor sleep and 100 at the right end representing good sleep). The average score of the five dimensions was the total score of the scale, ranging from 0 to 100, with a higher score indicating superior sleep quality. In this study, the Cronbach’s α coefficient of the RCSQ scale was 0.893. ② Polysomnography (PSG) was conducted using the ASE-2012 PSG system (Guangzhou Andite Medical Technology; Medical Device Registration No. GD 20192071045). The following parameters were quantified: frequency of nocturnal awakenings, slow-wave sleep (SWS) duration (minutes) and total sleep time (TST; minutes). (3) Perceived stress, mood state and psychological distress were assessed at postoperative day 1 and week 1 using the Perceived Stress Scale (PSS-10), the Brief Profile of Mood States (BPOMS) and the Hospital Anxiety and Depression Scale (HADS), respectively. The PSS-10, originally developed by Cohen et al.[22] and translated into Chinese by Wang et al.,[23] consists of 10 items scored from 0 (never) to 4 (very often), yielding a total score ranging from 0 to 40, with higher scores indicating greater perceived stress. The Chinese version of the BPOMS, adapted by Chi et al.[24] from the original by Grove et al.,[25] assesses six domains (I. Confusion, II. Tension, III. Vigor, IV. Anger, V. Depression and VI. Fatigue). Each domain contains five items rated on a 5-point Likert scale from 0 (not at all) to 4 (extremely). The total score ranges from 0 to 120, with higher scores reflecting more severe negative mood states. The HADS, developed by Zigmond and Snaith[26] and validated in Chinese by Sun et al.,[27] comprises two subscales (anxiety and depression), each containing 7 items scored 0–3. Subscale scores range from 0 to 21, interpreted as follows: 0–7 (no symptoms), 8–10 (possible symptoms) and 11–21 (definite symptoms). The total score (0–42) indicates the overall level of psychological distress, with higher scores signifying greater severity. In this study, the Cronbach’s α coefficients for the PSS-10, BPOMS and HADS were 0.825, 0.786 and 0.907, respectively.
Schedule and Methods for Outcome Assessments
(1) Haemodynamic parameters
DBP, SBP and HR were measured at 7:00–8:00 am on postoperative day 1 and week 1. Measurements were obtained using the same electronic sphygmomanometer after patients had fasted and rested supine for 15 minutes. Three consecutive readings were obtained, and the mean value was recorded for analysis.
(2) Sleep quality
① RCSQ: Assessments were conducted on the morning following postoperative day 1 and week 1. Nurses administered the questionnaire via a one-on-one interview, guiding patients through completion. Scores were verified and recorded immediately.
② PSG parameters: Overnight PSG was performed on the nights corresponding to postoperative day 1 and week 1. Technicians conducted continuous monitoring (≥6 hours), covering the period from habitual sleep onset to spontaneous morning awakening. Data were automatically collected, with two independent technicians reviewing artifacts and arousal events before finalising parameters for database entry.
(3) PSS-10, BPOMS and HADS scales
These scales were administered once at each time point (postoperative day 1 and week 1) between 9:00 and 11:00 am when patients were alert. Nurses provided paper versions and instructed patients to complete them independently. For patients with visual impairment, nurses read items aloud and recorded responses verbatim without leading prompts. All scales were collected immediately and reviewed for completeness.
Statistical Methods
Data organisation and table creation were performed using Microsoft Excel (Version 2206, Microsoft Corporation, Redmond, WA, USA). Statistical analyses were conducted using SPSS software (Version 27.0, IBM Corp., Armonk, NY, USA). The normality of continuous variables was assessed using the Shapiro–Wilk test. Normally distributed data were presented as mean ± standard deviation and were compared between groups using the independent samples t-test and within groups using the paired samples t-test. Categorical data were expressed as counts (percentages) and compared using the chi-square test. A two-sided P < 0.05 was considered statistically significant. Furthermore, analysis of covariance (ANCOVA) was employed to compare outcomes at postoperative week 1 between groups, adjusting for covariates including the respective baseline value measured at postoperative day 1 and the time covariate (converted to a continuous variable representing the number of days from 1 January 2022 to the patient’s admission date).
RESULTS
Baseline Data
All baseline characteristics, including age; sex; coronary artery (CA) stenosis severity; NYHA functional classification; CHD subtype (STEMI, UA and NSTEMI); culprit vessel location (left anterior descending, left circumflex and right CA); comorbidities; number of diseased vessels; stent length; stent diameter; post-PCI antiplatelet regimen; educational attainment; body mass index; average daily sleep duration 1 month prior to PCI; history of insomnia within the preceding 6 months and PSS-10 score 1 week before PCI; demonstrated satisfactory balance between the two groups (P > 0.05; Table 1).
Table 1.
Comparison of baseline characteristics between groups after propensity score matching
| Indicator | Conventional group (n = 53) | BBT group (n = 51) | χ2/t | P | |
|---|---|---|---|---|---|
| Age (years) | 67.64 ± 5.19 | 66.85±5.47 | t = 0.756 | 0.452 | |
| Gender | Male | 31 (58.49) | 27 (52.94) | χ2 = 0.325 | 0.569 |
| Female | 22 (41.51) | 24 (47.06) | |||
| CA stenosis severity | 70.49 ± 3.58 | 71.12±3.79 | t = 0.872 | 0.385 | |
| NYHA functional classification | Level II | 26 (49.06) | 29 (56.86) | χ2 = 0.636 | 0.425 |
| Level III | 27 (50.94) | 22 (43.14) | |||
| CHD subtypes | STEMI | 41 (77.36) | 39 (76.47) | χ2 =0.179 | 0.914 |
| UA | 5 (9.43) | 6 (11.76) | |||
| NSTEMI | 7 (13.21) | 6 (11.76) | |||
| Location of the diseased blood vessel | Left anterior descending | 33 (47.83) | 30 (44.12) | χ2 = 1.036 | 0.596 |
| Left circumflex | 12 (17.39) | 9 (13.24) | |||
| Right coronary artery | 25 (36.23) | 29 (42.65) | |||
| Comorbidities | Hypertension | 18 (33.96) | 14 (27.45) | χ2 = 0.517 | 0.472 |
| Diabetes | 10 (18.87) | 8 (15.69) | χ2 = 0.184 | 0.668 | |
| Hyperlipidaemia | 15 (28.30) | 17 (33.33) | χ2 = 0.309 | 0.578 | |
| Number of diseased vessels | One | 37 (69.81) | 34 (66.67) | χ2 = 0.119 | 0.731 |
| Two | 16 (30.19) | 17 (33.33) | |||
| Post-PCI antiplatelet regimen | Double joint | 43 (81.13) | 45 (88.24) | χ2 = 1.007 | 0.316 |
| Triad | 10 (18.87) | 6 (11.76) | |||
| Stent diameter (mm) | 2.71 ± 0.34 | 2.65±0.32 | t = 0.926 | 0.357 | |
| stent length (mm) | 22.46 ± 2.12 | 22.14±2.08 | t = 0.777 | 0.439 | |
| Educational attainment | High school and below | 36 (67.92) | 38 (74.51) | χ2 = 0.549 | 0.459 |
| College degree or above | 17 (32.08) | 13 (25.49) | |||
| BMI (kg/m2) | 24.11 ± 1.45 | 23.86±1.31 | t = 0.922 | 0.359 | |
| Average Daily Sleep Duration (hours), 1 month pre-PCI | 5.38 ± 1.05 | 5.45±1.02 | t = 0.345 | 0.731 | |
| History of Insomnia, within 6 months pre-PCI | Yes | 12 (22.64) | 10 (19.61) | χ2 = 0.143 | 0.705 |
| No | 41 (77.36) | 41 (80.39) | |||
| PSS-10 Score, 1 week pre-PCI | 27.26 ± 3.23 | 26.95 ± 3.17 | t = 0.494 | 0.623 | |
Note: BMI, body mass index; CA, XXX???; CHD, coronary heart disease; NSTEMI, non-ST-segment elevation acute coronary syndrome; NYHA, New York Heart; PCI, percutaneous coronary intervention; PSS-10, Perceived Stress Scale; STEMI, ST-elevated myocardial infarction; UA, unstable angina.
Haemodynamic Parameters
Compared with postoperative day 1, significant reductions in DBP, SBP and HR were observed at week 1 in both groups (P < 0.05). The BBT group demonstrated significantly greater reductions in these parameters compared with the routine care group (P < 0.05). Analysis of covariance (ANCOVA), adjusting for baseline values at day 1, confirmed significant between-group differences in DBP, SBP and HR at week 1 (P < 0.05; Table 2).
Table 2.
Comparative measurements of DBP, SBP and HR at 1 day and 1 week after surgery
| Group | DBP (mmHg) |
SBP (mmHg) |
HR (times/min) |
|||
|---|---|---|---|---|---|---|
| One day after surgery | One week after surgery | One day after surgery | One week after surgery | One day after surgery | One week after surgery | |
| Conventional group (n = 53) | 76.87 ± 6.49 | 71.78 ± 4.95* | 129.65 ± 10.34 | 122.73 ± 9.15* | 81.87 ± 6.62 | 75.41 ± 4.27* |
| BBT group (n = 51) | 76.12 ± 6.23 | 66.23 ± 3.48* | 128.73 ± 10.68 | 116.82 ± 6.49* | 80.95 ± 6.53 | 71.25 ± 3.64* |
| t | 0.601 | 6.591 | 0.446 | 3.786 | 0.713 | 5.355 |
| P | 0.549 | <0.001 | 0.656 | <0.001 | 0.477 | <0.001 |
| ANCOVA F | 38.62 | 22.15 | 29.84 | |||
| ANCOVA P | <0.001 | <0.001 | <0.001 | |||
Note: Compared with 1 day after surgery of this group, *P < 0.05; DBP, diastolic blood pressure; HR, heart rate; SBP, systolic blood pressure.
Sleep Quality
Compared with postoperative day 1, both groups showed significant improvements in RCSQ scores, PSG-measured deep sleep duration and total sleep time, along with a reduction in PSG-measured nocturnal awakenings at week 1 (P < 0.05). The BBT group demonstrated significantly greater improvements in RCSQ scores, deep sleep duration and total sleep time, as well as a more pronounced reduction in nocturnal awakenings, compared with the routine group (P < 0.05). ANCOVA, adjusting for baseline values at day 1, confirmed significant between-group differences in these parameters at week 1 (P < 0.05; Table 3).
Table 3.
Comparison of RCSQ scores and PSG parameters between the two groups at 1 day and 1 week after surgery
| Group | PSG parameter |
|||||||
|---|---|---|---|---|---|---|---|---|
| RCSQ score |
Nocturnal awakenings (episodes) |
Deep sleep duration (h) |
Total sleep time (h) |
|||||
| One day after surgery | One week after surgery | One day after surgery | One week after surgery | One day after surgery | One week after surgery | One day after surgery | One week after surgery | |
| Conventional group (n = 53) | 56.51 ± 5.28 | 76.48 ± 6.65* | 5.16 ± 1.04 | 2.26 ± 0.58* | 1.46 ± 0.34 | 2.17 ± 0.52* | 5.44 ± 1.12 | 6.93 ± 1.37* |
| BBT group (n = 51) | 57.09 ± 5.74 | 86.81 ± 7.47* | 5.03 ± 0.97 | 1.38 ± 0.27* | 1.52 ± 0.36 | 2.58 ± 0.65* | 5.57 ± 1.08 | 7.91 ± 1.56* |
| t | 0.537 | 7.455 | 0.659 | 9.855 | 0.874 | 3.559 | 0.602 | 3.408 |
| P | 0.593 | <0.001 | 0.512 | <0.001 | 0.384 | <0.001 | 0.548 | <0.001 |
| ANCOVA F | 45.33 | 63.21 | 18.76 | 12.94 | ||||
| ANCOVA P | <0.001 | <0.001 | <0.001 | <0.001 | ||||
Note: Compared with 1 day after surgery of this group, *P < 0.05; RCSQ, Richards–Campbell Sleep Questionnaire; PSG, polysomnography.
Perceived Stress Levels and Mood States
Compared with 1 day after surgery within the same group, both groups exhibited significant reductions in PSS-10 and BPOMS scores at 1 week after surgery (P < 0.05). Furthermore, the BBT group demonstrated significantly lower PSS-10 and BPOMS scores than the conventional group (P < 0.05; Figure 4).
Figure 4.
Comparison of PSS-10 and BPOMS scores between the two groups at 1 day and 1 week after surgery. Note: Figure A shows the PSS-10 score; Figure B shows the BPOMS score; *** indicates that the comparison between the two groups is significant at P < 0.001.
Psychological Distress Levels
Compared with 1 day after surgery within the same group, both groups showed significant reductions in HADS anxiety subscale scores, depression subscale scores and total HADS scores at 1 week after surgery (P < 0.05). Moreover, the BBT group exhibited significantly lower HADS anxiety subscale scores, depression subscale scores and total HADS scores than the conventional group (P < 0.05). ANCOVA, adjusting for baseline values at postoperative day 1, demonstrated statistically significant between-group differences in the HADS anxiety subscore, depression subscore and total score at week 1 (P < 0.05; Table 4).
Table 4.
Comparison of HADS subscale scores and total scores between the two groups at 1 day and 1 week after surgery (scores)
| Group | HADS anxiety subscale scores |
HADS depression subscale scores |
Total HADS scores |
|||
|---|---|---|---|---|---|---|
| One day after surgery | One week after surgery | One day after surgery | One week after surgery | One day after surgery | One week after surgery | |
| Conventional group (n = 53) | 8.57 ± 1.68 | 5.13 ± 1.09* | 6.14 ± 1.15 | 4.62 ± 1.03* | 14.71 ± 3.37 | 9.75 ± 2.29* |
| BBT group (n = 51) | 8.62 ± 1.74 | 3.27 ± 0.92* | 6.28 ± 1.34 | 3.15 ± 0.87* | 14.90 ± 3.45 | 6.42 ± 1.36* |
| t | 0.149 | 9.386 | 0.573 | 7.848 | 0.284 | 8.972 |
| P | 0.882 | <0.001 | 0.568 | <0.001 | 0.777 | <0.001 |
| ANCOVA F | 47.62 | 39.35 | 43.48 | |||
| ANCOVA P | <0.001 | <0.001 | <0.001 | |||
Note: Compared with 1 day after surgery of this group, *P < 0.05; HADS, Hospital Anxiety and Depression Scale.
DISCUSSION
Compared with the routine care group, the BBT group exhibited significantly lower DBP, SBP and HR levels; higher RCSQ scores, PSG-measured slow-wave sleep duration and total sleep time; fewer nocturnal awakenings and lower PSS-10 scores, BPOMS scores, HADS anxiety and depression subscores and total HADS scores at the 1-week postoperative assessment. These results suggested that BBT acoustic stimulation is an effective non-pharmacological management strategy, contributing to improved haemodynamic stability, enhanced sleep quality, ameliorated mood state and reduced perceived stress and psychological distress in elderly patients following PCI.
Jang et al.[28] demonstrated that BBT-based music alleviates anxiety and pain and mitigates effects on vital signs such as HR in surgical patients. A randomised controlled trial by Loong et al.[29] involving cataract surgery patients further confirmed that BBT music reduces haemodynamic parameters (including HR and DBP) and anxiety levels. Building on existing literature and the present findings, we postulate that haemodynamic modulation by BBT may be mediated through the following pathways. Firstly, BBT acoustic stimulation may induce cortical θ/α wave synchronisation via the ASSR, thereby inhibiting stress-related neural circuits involving the prefrontal cortex and amygdala. This suppression reduces sympathetic nervous system activity, indirectly attenuates renin–angiotensin–aldosterone system activation and consequently decreases peripheral vascular resistance and myocardial oxygen consumption. Secondly, BBT may modulate the sleep–wake cycle through the FFR, facilitating the transition from β to θ/δ waves, prolonging slow-wave sleep and promoting physiological recovery. Thirdly, the sensory input provided by BBT may divert patients’ attentional focus from postoperative discomfort, reducing somatisation-induced physiological fluctuations.[30,31]
Bavafa et al.[32] highlighted BBT music therapy as a cost-effective acoustic-based treatment, noting that theta-range binaural beats can effectively modulate electroencephalographic patterns in patients with primary insomnia, facilitating a rapid transition from wakefulness to sleep. The improvement in sleep quality observed in our study may be attributed to the following mechanisms. Age-related degeneration of the brainstem reticular formation compromises sleep maintenance in elderly patients. Theta oscillations play a crucial role in memory consolidation and deep relaxation. BBT enhances theta wave synchronisation, stimulating the auditory cortex and eliciting an FFR. This promotes a shift in neural oscillations from beta waves (13–30 Hz, characteristic of wakefulness) to alpha (8–13 Hz, relaxation), theta (4–7 Hz, early sleep) and delta waves (0.5–4 Hz, deep sleep). Concurrently, enhanced alpha/theta activity in the prefrontal and parietal cortices suppresses cortical hyperarousal, reduces ruminative thinking (e.g., concerns about postoperative recurrence or disease prognosis), shortens sleep onset latency and increases duration of the N3 stage of non-rapid eye movement sleep (slow-wave sleep). These changes collectively improve sleep architecture and enhance the restorative quality of sleep.[33]
This study demonstrated that BBT acoustic stimulation therapy improved mood states and reduced perceived stress and psychological distress in elderly patients with CHD, and these findings were directly supported by Opartpunyasarn et al.[34] and Yang et al.[35] The underlying mechanism may involve binaural beat music guiding patients to autonomously adjust their respiratory rate to the rhythm, enhancing cardiorespiratory interaction via ‘resonance frequency’ and reducing the activity of noradrenergic neurons in the locus coeruleus. This process physiologically interrupts the somatic feedback loop of anxiety, thereby mitigating the generation of anxious and depressive feelings.
BBT acoustic stimulation therapy offers three primary practical advantages. Firstly, its ease of implementation − requiring only portable audio players and noise-cancelling headphones − allows for standardised, preset audio sessions delivered directly at the bedside. This eliminates the need for patient transfer to a dedicated therapy space, adapts to various positions and does not interfere with essential postoperative monitoring or intravenous therapy, making it particularly suitable for bedridden elderly PCI patients. Secondly, nursing staff can master core procedures (e.g., device setup and headphone fitting) after brief training. The therapy can conclude automatically via timed reminders, requiring no continuous supervision and adding minimal burden to nursing workloads. Thirdly, as a non-contact and non-pharmacological approach, BBT minimises patient resistance. Its immediate relaxing effects enhance perceived benefit, potentially improving long-term adherence and supporting sustained postoperative recovery.
Notably, elderly PCI patients often present with polypharmacy, sensory decline and reduced cardiovascular reserve, so their physiological and psychological responses may differ from general surgical or insomnia populations. Although this study controlled for variations in sensory processing capacity through strict hearing screening and exclusion criteria, the generalisability of findings should be approached with caution.
This study had several limitations. Firstly, as a retrospective analysis, the sample size was determined by available historical data rather than a priori power calculation, potentially resulting in an underpowered study. Secondly, the relatively small sample was drawn exclusively from elderly PCI patients at a single institution, which may limit the generalisability of the findings due to potential regional and institutional specificities. Thirdly, the core parameters of the BBT protocol were not fully standardised (e.g., variability in beat frequencies and background music types), potentially compromising internal consistency. Furthermore, only short-term outcomes during the 1-week postoperative hospitalisation were assessed, leaving the sustainability of effects beyond discharge unknown. Fourthly, the BBT incorporated multiple elements (binaural beats and background music), whereas the control group lacked an active comparator (e.g., non-beat music or white noise), causing difficulty in distinguishing specific BBT effects from general relaxation or placebo effects.
Future research should adopt a prospective, randomised controlled design with a large sample size determined by a priori power analysis to enhance statistical robustness; include control groups such as routine care plus non-beat music, or even a three-arm design with a blank control, an active placebo (standard music therapy) and the BBT group to isolate the specific effect of binaural beats; extend the follow-up period to evaluate the potential of BBT in post-discharge home-based rehabilitation and incorporate simultaneous monitoring of objective physiological indices like HRV and electroencephalogram to further elucidate the mechanism of BBT-induced physiological regulation.
CONCLUSION
In conclusion, BBT sound stimulation therapy demonstrates efficacy in improving postoperative haemodynamics, mood states and sleep quality while reducing perceived stress and psychological distress in elderly patients with CHD following PCI.
Availability of Data and Materials
The original contributions presented in the study are included in the article. Further inquiries can be directed to the corresponding author.
Author Contributions
Yang Jiao: study design, data analysis, manuscript writing.
Jingbo Ma: clinical data collection, literature review.
All authors are jointly responsible for the integrity of the entire work from the beginning to the publication of the article.
Ethics Approval and Consent to Participate
The study was approved by the Institutional Ethics Committee of People’s Hospital of Baishan (Ethics Review KY2025008) with informed consent from all participants.
Conflicts of Interest
The authors declare that there are no conflicts of interest.
Acknowledgment
No.
Funding Statement
No.
REFERENCES
- 1.Martin SS, Aday AW, Allen NB, Almarzooq ZI, Anderson CAM, Arora P, et al. American Heart Association Council on Epidemiology and Prevention Statistics Committee and Stroke Statistics Committee. 2025 Heart Disease and Stroke Statistics: A Report of US and Global data from the American Heart Association. Circulation. 2025:151e41–e660. doi: 10.1161/CIR.0000000000001303. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Center For Cardiovascular Diseases the Writing Committee of the Report on Cardiovascular Health and Diseases in China N. Report on cardiovascular health and diseases in China 2023: an updated summary. Biomed Environ Sci. 2024;37:949–92. doi: 10.3967/bes2024.162. [DOI] [PubMed] [Google Scholar]
- 3.Dai H, Much AA, Maor E, Asher E, Younis A, Xu Y, et al. Global, regional, and national burden of ischaemic heart disease and its attributable risk factors, 1990-2017: results from the Global Burden of Disease Study 2017. Eur Heart J Qual Care Clin Outcomes. 2022;8:50–60. doi: 10.1093/ehjqcco/qcaa076. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990-2021: a systematic analysis for the Global Burden of Disease Study 2021. Lancet. 2024;403:2100–32. doi: 10.1016/S0140-6736(24)00367-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Tao S, Tang X, Yu L, Li L, Zhang G, Zhang L, et al. Prognosis of coronary heart disease after percutaneous coronary intervention: a bibliometric analysis over the period 2004–2022. Eur J Med Res. 2023;28:311. doi: 10.1186/s40001-023-01220-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Calegari IB, Borges E, Silva L, Silva FF, Dos Santos Felix MM, Raponi MBG, Barbosa MH. Physiological and psychological changes in patients undergoing percutaneous coronary intervention: an integrative review. Crit Care Nurse. 2025;45:13–24. doi: 10.4037/ccn2025959. [DOI] [PubMed] [Google Scholar]
- 7.Kang L, Li Y, Chen K, Chen X, Chu Q, Zhao X, et al. Effect of Baduanjin exercise on acute myocardial infarction in patients with anxiety and depression after percutaneous coronary intervention: a randomized controlled trial. Medicine (Baltimore) 2024;103:e40225. doi: 10.1097/MD.0000000000040225. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Huang L, Zhou J, Li H, Wang Y, Wu X, Wu J. Sleep behaviour and cardiorespiratory fitness in patients after percutaneous coronary intervention during cardiac rehabilitation: protocol for a longitudinal study. BMJ Open. 2022;12:e057117. doi: 10.1136/bmjopen-2021-057117. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Ashhad S, Kam K, Del Negro CA, Feldman JL. Breathing rhythm and pattern and their influence on emotion. Annu Rev Neurosci. 2022;45:223–47. doi: 10.1146/annurev-neuro-090121-014424. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Riedy SM, Smith MG, Rocha S, Basner M. Noise as a sleep aid: a systematic review. Sleep Med Rev. 2021;55:101385. doi: 10.1016/j.smrv.2020.101385. [DOI] [PubMed] [Google Scholar]
- 11.Lalanza JF, Lorente S, Bullich R, García C, Losilla JM, Capdevila L. Methods for heart rate variability biofeedback (HRVB): a systematic review and guidelines. Appl Psychophysiol Biofeedback. 2023;48:275–97. doi: 10.1007/s10484-023-09582-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Muhammad Khir S, Wan Mohd Yunus WMA, Mahmud N, Wang R, Panatik SA, Mohd Sukor MS, et al. Efficacy of progressive muscle relaxation in adults for stress, anxiety, and depression: a systematic review. Psychol Res Behav Manag. 2024;17:345–65. doi: 10.2147/PRBM.S437277. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Salehabadi N, Pakravan A, Rasti R, Pourasghar M, Mousavi SJ, Saravi ME. Can binaural beat music be useful as a method to reduce dental patients’ anxiety? Int Dent J. 2024;74:553–8. doi: 10.1016/j.identj.2023.11.009. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Demirci S, Sezer S. Effect of binaural beats on anxiety and tolerance in patients undergoing upper gastrointestinal endoscopy without sedation: a randomized controlled trial. J Integr Complement Med. 2024;30:1209–16. doi: 10.1089/jicm.2023.0804. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Lin PH, Fu SH, Lee YC, Yang SY, Li YL. Examining the effects of binaural beat music on sleep quality, heart rate variability, and depression in older people with poor sleep quality in a long-term care institution: a randomized controlled trial. Geriatr Gerontol Int. 2024;24:297–304. doi: 10.1111/ggi.14827. [DOI] [PubMed] [Google Scholar]
- 16.Mujib MD, Rao AZ, Haque MFU, Alokaily AO, Hussain SS, Aldohbayb AA, et al. Modulated theta band frequency with binaural beat stimulation correlates with improved cognitive scores in Alzheimer’s patients. Front Aging Neurosci. 2025;17:1543282. doi: 10.3389/fnagi.2025.1543282. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.World Medical Association. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human participants. JAMA. 2025;333:71–4. doi: 10.1001/jama.2024.21972. [DOI] [PubMed] [Google Scholar]
- 18.Knuuti J, Wijns W, Saraste A, Capodanno D, Barbato E, Funck-Brentano C, et al. 2019 ESC guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J. 2020;41:407–77. doi: 10.1093/eurheartj/ehz425. [DOI] [PubMed] [Google Scholar]
- 19.Fihn SD, Gardin JM, Abrams J, Berra K, Blankenship JC, Dallas AP, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2012;60:e44–e164. doi: 10.1016/j.jacc.2012.07.013. [DOI] [PubMed] [Google Scholar]
- 20.Richards KC, O’Sullivan PS, Phillips RL. Measurement of sleep in critically ill patients. J Nurs Meas. 2000;8:131–44. [PubMed] [Google Scholar]
- 21.Chen LX, Ji DH, Zhao QY, Wang ZL, Wang L, Liang Y. Reliability and validity of Chinese version of Richards-Campbell Sleep Scale. Chinese J Nurs. 2016;51:1141–4. [Google Scholar]
- 22.Cohen S, Kamarek T, Mermelstein R. A globalmeasure of perceived stress. J Health Soc Behav. 1983;24:385–96. [PubMed] [Google Scholar]
- 23.Wang Z, Chen J, Boyd JE, Zhang H, Jia X, Qiu J, et al. Psychometric properties of the Chinese version of the Perceived Stress Scale in policewomen. PLoS One. 2011;6:e28610. doi: 10.1371/journal.pone.0028610. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Chi S, Lin WJ. The preliminary revision of brief mood scale (BPOMS) Chin Mental Health J. 2003;17: 768-70, 767. Chinese [Google Scholar]
- 25.Grove JR, Prapavessis H. Preliminary evidence for the reliability and validity of an abbreviated profile of mood states. Int J Sport Psychol. 1992;23:93–109. [Google Scholar]
- 26.Zigmond AS, Snaith RP. The hospital anxiety and depression scale. Acta Psychiatr Scand. 1983;67:361–70. doi: 10.1111/j.1600-0447.1983.tb09716.x. [DOI] [PubMed] [Google Scholar]
- 27.Sun ZX, Liu HX, Jiao LY, Zhou T, Yang LN, Fan JY. Reliability and validity of the Hospital Anxiety and Depression Scale. Chin J Clin. 2017;11:198–201. [Google Scholar]
- 28.Jang YJ, Choi YJ. Effects of nursing care using binaural beat music on anxiety, pain, and vital signs in surgery patients. J Perianesth Nurs. 2022;37:946–51. doi: 10.1016/j.jopan.2022.04.009. [DOI] [PubMed] [Google Scholar]
- 29.Loong LJ, Ling KK, Tai ELM, Kueh YC, Kuan G, Hussein A. The effect of binaural beat audio on operative pain and anxiety in cataract surgery under topical anaesthesia: a randomized controlled trial. Int J Environ Res Public Health. 2022;19:10194. doi: 10.3390/ijerph191610194. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Ingendoh RM, Posny ES, Heine A. Binaural beats to entrain the brain? A systematic review of the effects of binaural beat stimulation on brain oscillatory activity, and the implications for psychological research and intervention. PLoS One. 2023;18:e0286023. doi: 10.1371/journal.pone.0286023. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Lazzouni L, Ross B, Voss P, Lepore F. Neuromagnetic auditory steady-state responses to amplitude modulated sounds following dichotic or monaural presentation. Clin Neurophysiol. 2010;121:200–7. doi: 10.1016/j.clinph.2009.11.004. [DOI] [PubMed] [Google Scholar]
- 32.Bavafa A, Foroughi A, Jaberghaderi N, Khazaei H. Investigating the efficacy of theta binaural beat on the absolute power of theta activity in primary insomniacs. Basic Clin Neurosci. 2023;14:331–40. doi: 10.32598/bcn.2021.2162.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Lee M, Lee HJ, Ahn J, Hong JK, Yoon IY. Comparison of autonomous sensory meridian response and binaural auditory beats effects on stress reduction: a pilot study. Sci Rep. 2022;12:19521. doi: 10.1038/s41598-022-24120-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Opartpunyasarn P, Vichitvejpaisal P, Oer-Areemitr N. The effect of binaural beat audio on anxiety in patients undergoing fiberoptic bronchoscopy: a prospective randomized controlled trial. Medicine (Baltimore) 2022;101:e29392. doi: 10.1097/MD.0000000000029392. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Yang SY, Lin PH, Wang JY, Fu SH. Effectiveness of binaural beat music combined with rhythmical photic stimulation on older people with depressive symptoms in long-term care institution: a quasi-experimental pilot study. Aging Clin Exp Res. 2024;36:86. doi: 10.1007/s40520-024-02737-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
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Data Availability Statement
The original contributions presented in the study are included in the article. Further inquiries can be directed to the corresponding author.