Development and Deployment of a Music Listening Intervention Mobile Application for a Two-Group Blinded Randomized Clinical Trial

Abstract

Music is one nonpharmacological intervention to reduce anxiety and stress for mechanically ventilated patients. Efficient delivery of a music listening intervention can be enhanced through digital tools such as a mobile application (app) loaded onto an electronic tablet device. The objective of this study is to describe the iterative development and deployment of a novel app (Soundese) to deliver, record, and retrieve data associated with a two-arm randomized, blinded clinical trial testing music listening intervention compared to control silence condition on delirium severity among critically ill intensive care unit (ICU) older adult patients receiving mechanical ventilatory support. The Soundese mobile app was developed to deliver either experimental music listening intervention or a silence control listening condition to a sample of older adults receiving mechanical ventilatory support in the ICU and retrieve all protocol data. The Soundese app was developed using the Swift software language and is compatible with all iOS devices. The Soundese app consists of two components: (1) a mobile app that delivers the assigned, blinded listening intervention from an iPad through headphones to each subject and automatically logs each listening session, its duration, the randomization arm, and uploads these data to a server, and (2) an analysis app that generates a spreadsheet with summarized data of the respective listening session, music details, and reports for further analyses. A Dropbox application programmer interface enabled the secure storage of files on a designated Dropbox account. After initial field testing and iterative development changes based on research staff feedback, the Soundese app delivers the assigned experimental listening condition or silence control condition when deployed remotely in the field. The app’s mobile nature allows for immediate and automatic data capture, which is summarized for statistical analysis. There is no need for any manual recording of any intervention data by busy ICU staff, including listening time or music selections. The Soundese mobile app efficiently delivers the research protocol with fidelity and collects the necessary data for an ICU-based clinical trial. The app may be useful in other clinical trials testing music listening interventions in various settings or for deploying other audio-based interventions.

Introduction

The intensive care unit (ICU) is a specialized setting for treating patients who are severely ill and with life-threatening conditions, requiring 24/7 monitoring by highly trained staff (Stretch & Shepherd, 2021). The physiological stress of critical illness compounded by the psychological stress of being admitted to the high-tech environment of the ICU can contribute to adverse sequelae. While going through all the stress of the ICU, patients often experience delirium (acute confusion syndrome), pain, and anxiety. Music listening as a therapeutic intervention has a strong scientific basis supported by several studies on its effect on promoting health and well-being (Chen et al., 2021; Chlan & Heiderscheit, 2009; Chlan et al., 2013; Dingle et al., 2021; Viola et al., 2023).

Listening to music between 60 and 80 beats per minute has been reported to effectively manage symptoms such as pain, anxiety, and depression, and can reduce analgesic medication requirements (Chlan et al., 2013; Dayuan et al., 2022; Dingle et al., 2021; Lee et al., 2023; Zang et al., 2023). However, detailed protocols on how music listening interventions are delivered in clinical settings are infrequently reported in the literature. Furthermore, investigators need efficient methods to deploy interventions while maintaining fidelity to the protocol regardless of which research staff are responsible. This is particularly challenging with clinical trials with blinded arms. Moreover, notably absent from the literature are publications on how to deliver music listening interventions with fidelity for randomized clinical trials (RCTs), obtain complete and reliable data on the length and frequency of music listening interventions, and retrieve study data without losing any information (Cox et al., 2024). We detail here the iterative development of a novel mobile music listening and tracking application (app) deployed to meet the needs of a blinded, two-arm RCT conducted in the dynamic setting of the ICU.

Methods

Parent Clinical Trial Background and Patient Recruitment

Critically ill mechanically ventilated patients aged 50 and older without major neurological injury (i.e., traumatic brain injury) were recruited for this blinded RCT testing the efficacy of sequenced music listening to decrease the occurrence and severity of delirium, an acute brain dysfunction syndrome. Patients (n = 160) were randomized to either 60 min of music with noise-canceling headphones or a silence track twice daily for up to 7 days in the ICU. Details regarding the protocol for the parent RCT are available elsewhere (Seyffert et al., 2022).

Patients were recruited from two Indianapolis, IN hospital systems: Eskenazi Health and Indiana University Health and Mayo Clinic Rochester, MN. Research staff reviewed the electronic medical records of ICU patients daily for eligibility. Consent was obtained from patients or their authorized representatives. Patients were randomized 1:1 using a computer-generated list with block stratification by the hospital.

Development of the Soundese Mobile Application (App) for Music Listening and Intervention Tracking

Overview

Given the assigned listening sessions were delivered to patients by research staff blinded to the specific intervention condition, the specific listening session condition was activated from a central location by one unblinded member of the research staff prior to transporting the equipment to the respective ICU by blinded research staff. To maintain the integrity of the blinded condition while delivering the protocol with fidelity, a remotely delivered digital solution was sought whereby an application (app) would automatically log the specific date and length of time of each per protocol session, log-specific music selected or control silence track, with capabilities to automatically upload the data to a server and then effortlessly retrieve these data for further analyses.

The Soundese software research system is designed to provide investigators with data on the music listening habits of research participants and includes a mobile app and an analysis app. The mobile app provides protocol-specific songs and records each participant’s usage in a cloud-based database. At regular intervals, the database contents are sent, using an encrypted email, to the research coordinator who then uploads the files into the analysis app. The analysis app provides data and statistics regarding each participant’s music listening habits over each 24-hr period and for the duration of study participation.

Limitations and Challenges of Previous Systems

The current Soundese system represents the second iteration of a platform to support the necessary work of the clinical trial. The previous system was built using the Ionic cross-platform development system (Ionic Framework, 2023) for the mobile app and a custom Javascript-based backend for song storage and usage databases.

This first iteration of the system had several limitations. First, on the backend side, the music to be used had to be added to the online database using a custom Javascript app that needed to be more user-friendly as it required adding all existing music whenever one additional piece was to be added. Maintaining the correct music database was essential to obtaining the usage data already collected which proved challenging. Second, differences between Android and iOS devices made it difficult to provide a consistent control interface for the playback of the songs, particularly from lock screens. Third, while the backend dashboard provided the ability to browse the records within the database and had statistics on each participant’s usage but did not support raw records viewing or export to spreadsheets. Lastly, there were ongoing costs to maintain the backend server throughout the study.

Adaptations from Early Use and Iterative Development

Based on the limitations and challenges of the first system outlined above, the current system would only support Apple iPads without a backend, storing all data on the mobile device until uploaded through encrypted email to the researcher. A key adaptation was the creation of an analysis app to automatically generate a multi-tab spreadsheet containing raw data records, daily summary statistics, and summary statistics for each participant’s study enrollment duration.

Component 1: Soundese Mobile App for Music Listening

Technologies Used for Development

The Soundese mobile app, developed using the Swift software language, is compatible with all iOS devices. A Dropbox application programmer interface enables secure storage of music files on a designated Dropbox account. Although designed for all iPhones and iPads, this study used iPad Air exclusively.

Core Features of the App

The app comprises a music library with a minimum of 250 songs, enabling investigators or participants to create curated or personalized playlists for relaxation by selecting, sorting, or organizing tracks by genre. The app allows the participant to preview a track before making their selection. Its user-friendly interface is designed for easy operation by patients or caregivers with limited dexterity and playback controls are accessible on the lock screen which allows usage data to be tracked even while the device is locked. Moreover, the app automatically logs music playback details, including track selection and duration, which are linked to unique study IDs and transmitted via secure email.

Special Features of the App

The Soundese app offers the unique ability for silence-only playback, a crucial feature for control subjects. This function allows participants to listen to silence only while displaying comprehensive information about the track, including its playback duration, on the app’s user interface—an essential feature of the parent-blinded RCT (Seyffert et al., 2022). In addition, the app accommodates two distinct research roles. The first role belongs to the unblinded research coordinator, who possesses the authority to assign a participant identifier to the app and randomize participants to either the control or experimental intervention group. The second role is designated for the blinded research coordinator, who is restricted to deploying blinded assignments and initiating the secure uploading of data from the device. Music lists can be updated remotely without disrupting the stored data, and all updates synchronize with the app. To ensure compliance and backup, the app routinely dispatches the contents of the Usage and Music databases to the unblinded research coordinator via encrypted email at specified intervals.

Curated Music for the Soundese Mobile Music Listening and Tracking Application

Music is unique and sensorial, comprising a variety of musical elements that impact the listener’s experience as well as help in managing pain, anxiety, and depression (Dayuan et al., 2022; Lee et al., 2023; Rosetti, 2014; Zang et al., 2023). Since responses to music may be physical and emotional, careful selection and curation of the music was necessary to ensure the experimental music intervention addressed the needs of the study subjects (Heiderscheit, 2021; Heiderscheit et al., 2022; Rosetti, 2014). Furthermore, the selection and curation of the music by the music therapist helped to avoid the inclusion of music that may be startling, jarring, or foster unintended emotional responses (Heiderscheit et al., 2022). This entailed including music that was predictable, did not contain sudden changes, only some dynamic tension, and had a simplicity of musical elements (Heiderscheit, 2021; 2023; Hernandez-Ruiz et al., 2020). Careful curation of the music provided for a comfortable listening experience for study participants and avoided sudden shifts or changes in the music (such as a high degree of melodic or harmonic tension) as the listener transitioned from one piece of music to another (Bonde, 2019; Bonny, 1998; Hernandez-Ruiz et al., 2020). The curation process helped ensure there were no significant changes in the musical elements that may interfere with the subjects’ relaxation response as they engaged in the music listening experience (Bonde, 2019; Heiderscheit, 2023; Hernandez-Ruiz et al., 2020).

Music for intervention utilized in the parent clinical trial was curated by a board-certified music therapist who specifically focused on classical and contemporary relaxing music (60–80 bpm) to provide comfortable listening experiences and foster a relaxation response. These two genres of music were selected based on the music most commonly selected by participants in previous RCTs with mechanically ventilated patients (Chlan et al., 2013; Heiderscheit et al., 2022). The music was purchased from the iTunes Store with no usage restrictions (Digital Rights Management-free) and uploaded to DropBox. The BPM Counter^™ app was utilized to determine the bpm at the start, mid-point, and end of each piece of music. Playlists (comprising 281 unique pieces of music) began with music at a rate of 80 bpm, transitioning to 60 bpm, organized by instrumentation and tonality (key) to ensure smooth transitions. Music of similar instrumentation including string, brass, piano, and other instruments were grouped. Given music with similar dynamics from the previous piece was programmed together, this grouping intended to ensure a limited shift in musical dynamics for the listener. In addition, the order of the pieces in the same or a similar key was planned to avoid abrupt tonal changes that can detract from the listening experience (Heiderscheit et al., 2022). The curation process takes time and an understanding of musical elements. The playlists in the parent study were curated to gradually transition from 80 to 60 beats per minute across the participant’s listening experience. The control involved silence through headphones, chosen to avoid other cognitive stimuli, as audiobooks were not preferred by mechanically ventilated ICU patients in pilot testing.

Component 2: Soundese Analysis App

Technologies Used for Development

The analysis app was developed using the cross-platform development package Electron (2023), with versions compatible with Windows and Mac OS that researchers can use to evaluate the intervention characteristics.

Core Features of the Analysis App

The analysis app enables users to easily drag and drop Usage and Music database files within the app for processing. These files are then compiled into an Excel spreadsheet, summarizing each participant’s app activity to the date of file creation. This feature allows for intermediate compliance evaluations and comprehensive end-of-study reports.

The spreadsheet includes daily and total measurements, such as assessed music tracks with timestamps, playback frequency and duration, and a 24-hr usage histogram divided into 15-min intervals. Furthermore, the app calculates the total time spent on each music genre, providing genre-specific listening preferences. These core features enable investigators to gain an understanding of patient interaction with the app, enabling analysis and contributing to the study’s overall success.

Iterative Testing of the Music Listening and Tracking Application

We used feedback from patients enrolled in the Decreasing Delirium through Music pilot randomized controlled trial (Khan et al., 2020) to prioritize the following design elements in the Soundese application (app): (1) a visually uncluttered app interface that provides easy access to the most important controls (play/pause, rewind) for patients who may have limited dexterity and mobility in the ICU; (2) the ability to sort tracks by genre; and (3) rating music as favorites, marking music selections as liked or disliked. The layout and design elements of these important features were improved over time with successive versions of the app.

The app underwent two phases of testing in the clinical research environment as follows:

Phase I—using test IDs, running intervention and control modes in the ICU environment to ensure reliable data logging during periods with and without internet connectivity. Phase II—data recorded by the app in the background were validated against manual data recordings by research assistants in both test environments and with the first 10 participants enrolled in the clinical trial.

Deployment of the Soundese Music Listening and Tracking Application for a Clinical Trial

Upon enrollment and after randomization the study protocol utilizing the Soundese app is implemented as described below:

• Unblinded study coordinator programs iPad

  • Ensures data from the prior subject has been transmitted to a secure cloud storage account

  • Enters password to access unblinded programming mode

  • Enters new subject ID

  • Chooses control versus intervention mode based on randomization assignment

  • Coordinator closes out of programming mode resulting in the iPad app looking identical for each condition (control or experimental intervention listening)

• Headphones and iPad are cleaned per infection control standards.

• Coordinator prepares a listening session kit:

  • iPad

  • Noise canceling headphones (Sony Bluetooth WH-CH510 or SoundCore LifeQ20+ latex-free)

  • Remote control device

  • Cleaning wipes

• Listening session kit is delivered to the ICU/patient room accompanied by a checklist for monitoring intervention fidelity

Ethical considerations

The Indiana University Human Subjects Committee served as the IRB of record for the two-site parent RCT. Written informed consent was obtained from patients or their legally authorized representative (LAR) if patients were unable to consent due to mental status and/or altered level of consciousness. The informed consent process outlined the study protocol, participation length, risks and benefits, and withdrawal procedures. Patients were also informed that specimens collected from them for this study may be used for future research without further consent but without identifiable information.

The subjects were also made aware of our efforts to keep everything confidential, though absolute confidentiality could not be guaranteed. The informed consent document stated that the identity of the subject will be held in confidence in any published reports and databases.

Results

The Soundese mobile app with its two components, the mobile app and analysis app, enhances the delivery of the assigned listening session with fidelity, data capture, and seamless data retrieval. Figure 1 shows the music app home screen and Figure 2 shows the analysis app home screen.

Figure 1.

Enlarged Soundese app music display/home screen.

Figure 2.

Screenshot of analysis app display/home screen.

Analysis Components of the Soundese Application (app)

Data logged by the Soundese app during the assigned intervention is automatically saved. The Soundese app generates comprehensive spreadsheet reports that are then ready for data analysis inclusive of subject-level listening data and specific data on the music deployed during the music listening session (Figure 2). Tables 1 and 2 depict a selection of data generated by the analysis component of the Soundese app from a test subject.

Table 1.

DDM Trial Listening Session Deployment Checklist.

Equipment setup and functioning		Yes	No	Reason(s) for no
1.	Equipment in easy reach of the patient
2.	Cords/cables not tangled
3.	Cords/cables not hindering equipment
4.	Cords/cables not hindering catheters
5.	TV and other devices muted
6.	Signs posted reminding subject to use music
7.	“Hello Mr/s XXXX, I am here to start/stop your listening session. I am going to put the headphones on you and press play. You can adjust the volume using the buttons or adjust using the screen”
8.	Headphones powered on and connected
9.	iPad has adequate power (>20%)
10.	iPad screen and controls functioning
11.	Record starting/stopping time, vital signs, perform assessments
12.	Headphones placed on the patient prior to starting/stopping the listening session
13.	Notify the nurse when starting the listening session

Table 2.

Data from Soundese App's Music Listening Session of a Test Subject.

Data output variable	Output Result
Number of listening days	2
Total listening time (min)	434.3
Total songs/tracks listened to	77
Genre(s) listened to (name, #) over listening days	New Age, 32 Classical, 17
Average number of listening periods per day	1.5
Date and Timestamp for a single listening period	Artist	Genre	Listening time (min)
2022-08-19 11:57	Relaxing Music Jeff Victor & Laura MacKenzie	New Age	30

Protocol Delivery: Lessons learned with study equipment and the app

During the initial development and testing of the Soundese app and the protocol run-in phase, the connection between the headphones and the iPad was intermittently lost. A solution was implemented with a remote-control device to activate the randomized listening condition prior to entering the subject’s room. This strategy has successfully resulted in no further loss of connection between the headphones and the iPad.

An important aspect of the intervention involved activating the “loop” option in the Soundese app. This ensured that the randomized condition of either music listening, or silence played continuously during the 60-min intervention period without stopping after reaching the last song on the app or the end of the silence track. This prevented research staff from being exposed to the blinded condition or needing to reactivate the app to continue the listening session for the full 60 min.

Discussion

Music listening is a complex therapeutic intervention that has shown promise as a non-pharmacological intervention for multiple symptoms such as anxiety, pain, agitation, and depression (Dayuan et al., 2022; Lee et al., 2023; Viola et al., 2023; Zang et al., 2023). Music results in a reduction in inflammatory cytokines, decreases cortisol production, and dampens central nervous system arousal through diminished norepinephrine release; pathways implicated in the stress response contributing to multiple disease states (Nelson et al., 2008). Despite these benefits, gaps remain in the delivery of music interventions, including measuring the fidelity of music intervention delivery with precision, reliable data on intervention dose (length and frequency), and data retrieval for future use.

To address these challenges, we developed Soundese, a music delivery app designed to enhance the precision and usability of testing music interventions for relaxation. This manuscript outlines the iterative development of the Soundese app, including pilot testing in a randomized trial within the ICU. An earlier version of the Soundese app underwent pilot testing in a randomized trial to demonstrate its feasibility and the ability to be deployed in the complex, dynamic, and chaotic setting of the ICU. The Soundese app was not only able to maintain the integrity of the blinded condition while delivering the protocol, but it also automatically logged the length of time of each music delivery session, thereby providing objective fidelity data. The app was also able to log the silence-only control condition, and automatically uploaded the data to a server, which could be retrieved afterward for further analyses. An evolving music library currently at 250 pieces provided choices to the participants who could select and listen to their preferred music and create personal playlists. In addition, a user-friendly interface optimized usability for patients or caregivers with limited dexterity. At present, to the best of our knowledge, similar music applications (apps) that combine high fidelity of intervention delivery, continuous automated data collection, and a patient-friendly user-interface are not widely available.

The Soundese app represents an advancement over current practices in the healthcare system. It seamlessly incorporates a human–technology interface to deliver a holistic patient-centric intervention with an element of choice and control for both patients and their caregivers. With an ever-increasing technology landscape in healthcare, it is imperative that new applications be developed with patients, informal caregivers, and healthcare personnel input. Furthermore, technology needs to be rigorously field-tested, modified, and re-tested in applicable settings, which will allow for optimal integration in patient care without workflow disruption or increasing the burden on patients and healthcare providers. Only in this manner, will non-pharmacological interventions such as music listening be seamlessly implemented and sustained into clinical settings.

Limitations

There are a few limitations with the current version of the Soundese app that will require revisions prior to future clinical trial deployment. Future iterations of the Soundese app include the ability to automatically reset the app between participants. Currently, each time a new subject is randomized, it is necessary to delete, re-download, and re-sync the Soundese app to Dropbox to activate the assigned condition. Other revisions to the app include rewriting the app to accommodate any smart handheld device or electronic tablet and operating systems beyond iOS. Lastly, future iterations of the app may contain suggestions from patients themselves to improve the user experience.

Conclusions

The Soundese app efficiently delivers a music listening intervention protocol with fidelity and collects the necessary data for an ICU-based RCT. Reliable apps with high intervention fidelity will provide urgently needed granular data on the dose of music listening which will not only enhance reproducibility in future studies but will allow for effective music listening delivery implantation in real-life clinical settings. The app may be useful in other trials deploying audio-focused interventions.

Biographies

Author Biographies

Linda L. Chlan, PhD, RN, ATSF, FAAN, is the Associate Dean for Nursing Research and Professor of Nursing, Division of Nursing Research, Department of Nursing at Mayo Clinic.

Joseph Hunter Downs III, PhD, is a Research Associate at the Mayo Clinic in Rochester, MN, and the CEO of Area 10 Labs and Emercent Technologies.

Annie Heiderscheit, PhD, MT-BC, MFT, is a Professor of Music Therapy and Director of the Cambridge Institute for Music Therapy Research at Anglia Ruskin University in Cambridge, England.

Sikandar H. Khan, DO, MS, is an Assistant Professor of Medicine in the Division of Pulmonary and Critical Care Medicine at Indiana University School of Medicine, and Physician Scientist at Indiana University Center for Aging Research, Regenstrief Institute.

Salwa Moiz, MD, is a Research Specialist at the Regenstrief Institute, Inc., and a master’s student in the Health Informatics program at Indiana University—Indianapolis.

Babar A. Khan MD, MS, is a Professor of Medicine at Indiana University School of Medicine and a Research Scientist at Regenstrief Institute Inc., Indianapolis, IN.

Data Availability

After acceptance for publication manuscripts from the specific aims of the parent clinical trial, deidentified data will be available upon request for reasonable use.