We used a convergent mixed methods design [23], in which qualitative data (semistructured interviews) and quantitative data (validated mHealth assessment scales and readability measures) were collected in parallel and analyzed independently and integrated at the interpretation level through narrative weaving by comparing qualitative themes with quantitative scale domains.

To maximize diverse subjective feedback, a qualitative study design was used to capture TGNC individuals’ baseline attitudes about voice and gender and their reactions to the Attuned app. The qualitative component of this study is reported in accordance with the COREQ (Consolidated Criteria for Reporting Qualitative Research) [24]; the completed checklist is provided in Checklist 1. Adult (≥18 years) individuals identifying as transgender, nonbinary, or gender-nonconforming were recruited via word of mouth and advertising through lesbian, gay, bisexual, transgender, queer, or questioning (LGBTQ+) community organizations nationwide. Participants were required to have access to an iPhone, since the first version of Attuned was available only for iOS at the time of our study. Recruitment was particularly focused on representing a wide array of gender identities, and sample size was determined by thematic saturation [25,26]; in total, 18 individuals participated.

Following informed consent, participants engaged in a one-on-one semistructured interview with one of 2 members of the research team (ILA or CPK) and completed a demographic survey. They were then given access to the Attuned app for one week and instructed to experience as much didactic material as possible. Following one week, participants were re-engaged for an additional semistructured interview, focused on their perspectives of the Attuned app and its delivery of GAVT. Screenshots of the app are shown in Figure 1. Interview questions were devised by the study team to collect information regarding (1) baseline attitudes about the voice and its relationship with gender, (2) prior experience with and impressions of voice training or self-driven voice modification, (3) impressions of the Attuned app in particular, and (4) reflections on the value and shortcomings of GAVT delivered by mHealth. Interviews were conducted via Zoom (Zoom Communications, Inc), and recordings were transcribed verbatim using a combination of Zoom’s built-in transcription (using a Health Insurance Portability and Accountability Act [HIPAA]–compliant Zoom platform) and the Whisper transcription app by OpenAI (which was run locally and through terminal, thus also achieving HIPAA compliance) [27]. Transcriptions were reviewed for accuracy by the individual who conducted the interview. All interviews took place between February and April 2025.

Interview transcriptions were coded using MaxQDA software (VERBI GmbH). Coding followed an inductive thematic analysis as described by Braun and Clarke [28]. Three authors (ILA, CPK, and RC) independently reviewed and coded the transcripts of the first 3 participants, both pre- and post-use interviews (ie, 6 transcripts in total). The 3 codebooks were then compared and reconciled through consensus discussion among all 3 coders to generate a finalized codebook. Prior to consensus discussion, inter-rater reliability of coding was calculated within MaxQDA, and the percent agreement was 95.7%, with a Cohen κ of 0.86, corresponding to near-perfect agreement. Two authors (ILA and CPK) then independently applied the finalized codebook to all remaining transcripts, with coding differences again reconciled via consensus discussion. No code required adjudication by a third coder. New codes arising during coding of the remaining transcripts were added to the codebook by consensus, and previously coded transcripts were reviewed again with the updated codebook. Thematic saturation was assessed following the approach of Guest et al [25], defined a priori as the point at which successive interviews yielded no new codes or themes. Codes were grouped into candidate themes and consolidated into 28 subthemes, which were reviewed and refined by the coding team into the 8 final themes reported below.

Two authors (IC and EO), with previous experience evaluating mHealth apps via validated scales and who were not involved in the development of Attuned, completed ratings via Google Forms. In line with prior systematic assessments of mHealth apps by members of our authorship team [21], the following scales were used: (1) the Mobile App Rating Scale (MARS) [29], (2) the Intercontinental Medical Statistics (IMS) Institute for Health Care Informatics Functionality Scores [30], (3) the Centers for Disease Control (CDC) Modified Clear Communication Index [31], (4) the Institute of Medicine (IOM) strategies for creating health-literate mHealth apps [32], (5) the Patient Education Materials Assessment Tool (PEMAT) [33], and (6) the System Usability Scale (SUS) [34]. No single validated scale captures quality, functionality, health literacy, and usability, so we applied the same multiscale battery used in our group’s prior systematic assessment of laryngology apps [21] to permit direct comparison with other apps. Scores were averaged between the 2 raters. For each of these scales with explicitly numerical output evaluated by 2 raters, interrater reliability was evaluated via calculation of an intraclass correlation coefficient (CA-ICC). Readability of the script used for didactic videos was also assessed using 5 validated readability formulas via Readable.io (Added Bytes Ltd) [35]: (1) Flesch-Kincaid Reading Level and Flesch-Kincaid Reading Ease [36], (2) the Gunning Fog Index [37], (3) Coleman-Liau Index [38], (4) Simple Measure of Gobbledygook (SMOG) Index [39], and (5) New Dale-Chall [40]. As previously described, it is standard to use multiple readability scales, as there is no established gold standard [41]. Each readability formula is calculated differently, focusing on various attributes of a given text selection such as word and sentence length, number of unfamiliar words, number of syllables, and sentence structure complexity. Briefly, the Flesch-Kincaid Reading Ease score ranges from 0 to 100 and is inversely related to readability, while the remaining scales describe a grade level of education necessary to understand the text [41].

The research team would like to formally acknowledge that our individual and collective identities may influence our research. We have opted to share information about the identities of the primary members of the research team who designed and conducted the majority of the present study.

ILA and CPK are both medical students and cisgender members of the LGBTQ+ community and are both advocates for gender-affirming care and the TGNC community. AR is a fellowship-trained laryngologist at the Sean Parker Institute for the Voice at the Weill Cornell Medical College, who completed her training at Stanford University and then at the University of California, Davis. She is a cisgender member of the LGBTQ+ community and an ally of the TGNC community. KAC is a fellowship-trained laryngologist at Stony Brook Medicine specializing in LGBTQ+ care, who trained at Oregon Health & Science University and then at the Sean Parker Institute for the Voice. He is a cisgender member of the LGBTQ+ community and an ally of TGNC people. MP is an SLP who trained at Ithaca College and later returned to direct the speech-language pathology clinic at the same institution. She is a cisgender woman and an LGBTQ+ ally. RC is a voice-specialized SLP, focusing on care of the professional voice and gender-affirming voice care (among other clinical specializations) at the Sean Parker Institute for the Voice, which trained at the Massachusetts General Hospital’s Institute of Health Professions. She is a cisgender woman and an ally to the LGBTQ+ community. All 6 team members underwent cultural humility training prior to beginning the development process.

This study received approval from the Weill Cornell Medical College Institutional Review Board (#22‐09025226). Informed consent was waived for this study, as the research presented no more than minimal risk to the participants and involved no procedures for which written consent is normally required outside of the context of research. Participants were provided with a study information sheet prior to joining the study. Participants were assigned a participant ID in REDCap (Vanderbilt University), and all survey data were captured in REDCap. Interviews were conducted over Zoom, and once the interviews were transcribed and all personal identifiers were redacted from the transcript using Whisper by OpenAI, which was run offline, the audio recordings of the interviews were destroyed upon completion of the study. Audio recordings and deidentified transcripts were stored locally on a password-protected tagged device and labeled with the participant ID. Participants received US $30 for their participation in the study and were compensated by ClinCard (Greenphire LLC).

MARS, SUS, and IMS scales were used to evaluate quality and functionality. The overall mean MARS score averaged between the 2 raters was 4.21/5 (SD 0.53), with the following scores for each subcategory: engagement 4.40/5 (SD 0.57), functionality 4.13/5 (SD 0.18), aesthetics 4.17/5 (SD 0.71), information 4.33/5 (SD 0.47), and subjective quality 4.0/5 (SD 0.71). However, interrater reliability, as measured by CA-ICC, was poor (0.348). The mean SUS score was 92.5/100 (SD 10.6), with an excellent CA-ICC of 0.912. The IMS score was 6.5 (SD 0.7) of the 11 recommended functions. Functions that both reviewers found to be missing were the ability to share and evaluate data, the provision of guidance based on user-entered information, and the provision of communication between health professionals and patients.

Next, Attuned was assessed with regard to health literacy via the CDC, IOM, and PEMAT scales. The CDC Clear Communication Index was 82.5% (SD 24.7 percentage points), slightly below the recommended “passing” score of 90%; missing elements largely pertained to the use of language, which is likely to be used by the audience, and to the use of chunked or bulleted text. The CA-ICC for this measure was also poor (0.347). The mean IOM score was 28.5 (SD 2.1) of 33 recommended strategies implemented within Attuned, with the “engage users” and “evaluate and revise your site” domains scoring lower. Both PEMAT actionability and understandability scores were 100%, with complete agreement between reviewers with a CA-ICC of 1.00.

Readability as determined by the Flesch-Kincaid Reading Level and the Gunning Fog Index scores was 5.6 and 7.9, respectively, both below the recommended eighth-grade reading level. The Flesch Reading Ease was 72.3, corresponding to roughly a seventh-grade reading level. However, the SMOG index was 9.3, signifying that 9.3 years of school education would be necessary to read the text, and the Coleman-Liau index also resulted in an eighth-grade reading level at 8.7. On the other hand, the New Dale-Chall score was 4.5, roughly corresponding to a fourth-grade reading level.

Qualitative and quantitative findings were integrated through narrative comparison and demonstrated substantial convergence. The high SUS score (92.5/100) converged with participants’ qualitative descriptions of the app as clear, well-structured, and easy to navigate (Theme 6). The IMS functionality assessment identified missing functions, such as provision of guidance based on user-entered information and communication between users and professionals, that mirrored the qualitative limitation theme of absent feedback and personalization (Theme 8). Similarly, the CDC Clear Communication Index fell below the passing threshold primarily on use of the audience’s own language, converging with participants’ requests for trans voices and greater dialect diversity in instructional content. Divergence was minimal: the strong PEMAT and readability results were consistent with participants’ descriptions of content as “digestible and easy to understand.”

In this mixed methods study, we have used qualitative methodology to (1) describe baseline attitudes toward voice and vocal modification among transgender individuals and (2) evaluate impressions of a free mobile app delivering clinically informed GAVT. We have also used a wide variety of validated mHealth-focused scales to assess the mobile app for functionality, usability, health literacy, and readability. Given the increasing focus on gender-affirming health care in the United States, the importance of both research on gender affirmation and easily accessible health interventions for TGNC individuals cannot be overstated. The findings of this study help to further establish the widespread demand and need for GAVT and to understand diverse user experiences with an initial iteration of an open-access novel GAVT mobile app for planned further improvement.

GAVT alone or in combination with surgery has been repeatedly shown to improve objective measures such as fundamental frequency, listener perceptions, and patient-reported outcome measures [45-47]. However, the vast majority of existing evidence is for voice feminization, since exogenous testosterone lowers vocal pitch among transmasculine individuals taking gender-affirming hormones, though many such individuals still report voice problems or dissatisfaction with their voices [48,49]. In addition, compared to the growing quantitative literature, relatively few qualitative studies have been undertaken to deepen understanding of factors affecting patients that are not adequately reflected in quantitative measures.

Our study uncovered several key themes among our study population at baseline, prior to use of the Attuned app. Participants consistently emphasized the importance of their voices as a key facet of their complete gender identity and as a determinant of their ability to be perceived by others in line with their gender. This is in line with prior qualitative studies of both transfeminine and transmasculine individuals, which have identified both internal self-confidence and experiences of misgendering as intimately linked to the voice [50-52]. An additional qualitative study by Holmberg et al [53] also noted the key contributions of the voice toward dysphoria, similar to our findings; although they did not explicitly explore dissatisfaction with the voice in parallel, they also identified a strong motivation among their participants to seek voice modification. Importantly, our inclusion of transgender men and nonbinary individuals alongside transgender women in our study population allowed for key perspectives regarding both trepidation and relative dissatisfaction with certain aspects of testosterone’s effects on the voice, highlighting that testosterone alone is sometimes insufficient for achieving vocal congruence. This solidifies the importance of further study among individuals seeking voice masculinization and further use of GAVT among this population. The phenomenon of an outwardly evident “trans guy kind of voice” that can present barriers to “passing” for transgender men is in line with existing knowledge that gender perception goes beyond simple pitch changes. A small number of previous qualitative studies have also raised similar concerns among transgender men who remain dissatisfied or continue to experience misgendering even after long-term testosterone use [52,54]. Furthermore, several nonbinary participants explicitly refrained from a binary feminization/masculinization framing of voice goals, describing both voice coaching and existing apps as engaging in “gender-boxing” that rendered them unusable (Q55, Q74). This underscores that voice modification goals cannot be inferred from gender identity alone and that both GAVT services and mHealth tools should accommodate individualized, nonbinary voice targets.

Contrary to most existing voice-related qualitative research among TGNC individuals, our study population consisted largely of individuals who desired but did not feel that they had access to GAVT. Our cohort also included individuals across a wide range of gender identities, geographic locations, ages, and prior experiences with various gender-affirming treatments. This allowed for substantial exploration of several areas that are not robustly represented in existing literature. For example, our findings regarding self-guided attempts at voice modification, including some practices that participants themselves worried could be causing vocal injury, offer an important glimpse into the vocal practices of TGNC individuals in a landscape of formal GAVT being inaccessible to many. Our findings regarding the importance of context in determining voice use and attempts at voice modification were in line with prior research [52]. Furthermore, our study uncovered not only themes regarding the inaccessibility of formal voice training but also several patterns of frustration with both publicly available online materials and prior voice-centered mobile apps, which substantially builds on prior work by Bush et al [55]. This represents a shortcoming of prior qualitative research in this field, which has largely recruited individuals already presenting to SLPs for GAVT, thus failing to capture the broad swath of the TGNC population who do not reach this point due to previously mentioned substantial barriers.

Our results also represent a largely positive reception among the first cohort of target users of Attuned from diverse geography, age groups, and gender identities. These results should be interpreted in light of the risk of acquiescence bias, given the interviewers’ membership in the development team, and are best understood as encouraging formative feedback rather than evidence of effectiveness. Despite technical glitches in the initial version of the app, participants looked favorably on the app’s content, structure, and tools to support their voice modification efforts. Participants emphasized the empowering nature of receiving detailed information about the mechanics of the voice and gender perception, in line with prior qualitative studies of individuals who have undergone GAVT [56,57]. Of note, qualitative literature investigating outcomes of GAVT is remarkably sparse, despite known shortcomings of quantitative measurements in this realm, such as lack of correlation between different patient-reported outcome measures or between these measures and objective acoustic outcomes [5,14]. This suggests that existing literature may not be adequately capturing the full depth of TGNC individuals’ experiences with GAVT and identifies a crucial area for further investigation.

Our study also uncovered substantial shortcomings of an app-based delivery of voice training, most prominently the lack of feedback and personalization. While certain aspects of these limitations will be intrinsic to any mobile app, advances in AI and biofeedback may allow future versions of Attuned to respond more robustly in real-time to users [58]. An additional consideration for app-based GAVT is the absence of clinical screening prior to training. In many institutional settings, laryngoscopic examination is recommended before initiating voice training to exclude underlying laryngeal pathology, whereas mobile apps are by nature accessible without professional evaluation. Attuned addresses this in part through an in-app disclaimer encouraging users with voice symptoms to seek evaluation by an otolaryngologist. Moreover, our qualitative findings suggest that in the current landscape, many TGNC individuals without access to formal care already attempt self-guided voice modification using unstructured online resources (including practices participants themselves worried could cause vocal injury). Structured, professionally designed guidance with appropriate safety recommendations may therefore represent a safer alternative to the unstructured resources many users currently rely on. It is also important to note that while some mobile apps focused on GAVT exist, most existing offerings range from free pitch-tracking with limited instructional material to structured instructional content available by subscription only [58-63]. TruVox (University of Cincinnati), a free web-based application, provides real-time pitch and resonance feedback alongside instructional content [58]. To the authors’ knowledge, Attuned is distinctive in combining a free sequential video curriculum narrated by voice clinicians with practice assignments and pitch-tracking in a native mobile app developed with a CAB.

With regard to the objective assessment of Attuned, scores on the battery of validated scales were high across quality, functionality, health literacy, and readability, though these tests were performed by members of the authorship team and should be interpreted accordingly. Attuned exceeded the previously published means of laryngology-focused mobile apps across all evaluated scales, notably achieving above 4/5 on the MARS scale and all associated subcategories, 100% on the PEMAT actionability and understandability scales, and resulting in scores below the benchmark of an eighth-grade reading level for the majority of readability scales [21]. Of note, our prior systematic assessment of laryngology mobile apps [21] did not use the SUS; however, Attuned’s score of 92.5 was well above the previously reported benchmarks of 68 and 80 across all digital health tools [64]. This reflects the goal of our app design and content creation process to develop a tool that would be readily available to users from around the country and with varying educational and socioeconomic backgrounds [22]. In addition, it should be noted that the version of the app subject to evaluation on these scales was the first version of the app ever made available and contained known glitches and deficits, which have already been targeted for improvement in future iterations. Future iterations of Attuned addressing these known deficits may perform differently, which will require further evaluation.

Despite its novel contributions, this study is not without limitation. First, while TGNC community members were intimately involved in the creation of Attuned and early plans for the qualitative portion of this study, we did not follow a strict community-based participatory research methodology without a governance structure, authorship opportunities, and fair compensation as previously described [22]. Given our group’s aspirations toward true community-based participatory research [22], this represents a crucial area of improvement for future studies of Attuned. A new CAB is currently being assembled to guide the revision process of the app, as well as to participate as co-investigators in future prospective research using Attuned.

While our use of semistructured interviews allowed deeper exploration of important themes, the necessary trade-off is that interviews were slightly different from each other and could not be directly compared. In addition, participants may have been subject to acquiescence bias, particularly in the post-Attuned interviews, whereby individuals may have felt subtle pressure to overemphasize positive attitudes toward Attuned, knowing that the interviewers were part of the app’s development team. We sought to partially mitigate this bias by asking open-ended questions to signal openness to any opinions that participants would share. Additionally, the objective assessment scales were completed by 2 authors. Although they were not involved in the app’s development, they were not independent of the study team, and these ratings therefore cannot be regarded as fully unbiased. Usability measures were not collected directly from study participants, which we have incorporated into the design of our planned prospective follow-up study. Furthermore, we did not apply exclusion criteria to potential participants (aside from requiring that they were identified within the TGNC umbrella). Our study may therefore be limited by selection bias, as participants choosing to participate in a study of GAVT are likely already interested in GAVT and are also highly motivated to pursue it; our study population—despite our best efforts to recruit broadly from across the country and to include a variety of gender identities and socioeconomic statuses—may thus have limited generalizability to the population of TGNC individuals at large. Participants’ specific voice modification goals (feminization, masculinization, androgynous, or other targets) were not captured as a survey item. Although gender identity distribution offers an approximation, these do not map neatly onto one another, and explicit characterization of voice goals will be incorporated into future studies. Our study did not collect backend information regarding each participant’s usage pattern or time spent on the app, which may have allowed for deeper analysis of participants’ impressions of the app. Finally, both interviewers are cisgender men and members of the LGBTQ+ community but not the TGNC community; this positionality, as previously mentioned, may have impacted the responses of some participants, who may have responded differently to non-LGBTQ+ interviewers or fellow TGNC individuals.

Future directions for our team include 2 directions. First, a revision of the Attuned app based on our participants’ feedback is currently underway, guided by a newly assembled CAB and addressing the technical issues identified in this study and expanding the diversity of voices represented in the instructional content. Planned future capabilities include personalized AI-driven guidance and real-time voice biofeedback to address the feedback and personalization limitations identified by participants, with development contingent on available funding and technical resources. Our team also plans a prospective, quantitative assessment of the app’s efficacy, including participant-administered usability measures, as compared with standard-of-care in-person GAVT. The present study also highlighted several important future directions for the field, including prioritization of studies of transgender men or other individuals seeking voice masculinization, outreach to populations without access to traditional GAVT, and expansion of overall qualitative study of TGNC individuals either seeking or after voice modification training in order to identify shortcomings and further improve outcomes for these individuals.

The voice is a crucial part of identity and interpersonal interactions for TGNC individuals, and many desire tools for voice modification but have difficulty accessing high-quality GAVT. In a landscape full of unstructured free resources of varying levels of trustworthiness, there is a critical unmet need for a structured, clinically informed curriculum that can be accessible at scale. Attuned, a free mobile app developed through a user-centered approach, was positively received by an initial cohort of TGNC users. While app-based training cannot replace the individualized feedback of one-on-one voice training, these findings suggest promise in expanding access to structured, professionally developed GAVT, to be confirmed in a prospective comparative study.