Understanding and treating depression is complex, particularly when capturing the daily experiences of those living with it. Researchers are now exploring a new approach: using the human voice to gain deeper insight into how people process, express and recover from depression, thanks to newly developed technology.
Fabla, a voice diary app for clinical research developed at Emory University, is central to a study on psilocybin’s effects in individuals with major depressive disorder. The app prompts participants to record daily spoken reflections before and after undergoing treatment, offering researchers a window into how their language and emotional state evolve in response to psilocybin-assisted therapy.
“Speech carries information we don’t always consciously recognize,” says Deanna Kaplan, PhD, director of the Human Experience and Ambulatory Technologies (HEAT) Lab at Emory University School of Medicine and creator of Fabla. “By allowing researchers and clinicians to ask questions participants answer aloud, we can capture markers of mental health contained in speech that reveal more than written words alone.”
Fabla is the first mobile app enabling researchers to securely collect participants’ speech biomarkers throughout their daily life. Speech biomarkers are subtle patterns in a person’s voice, such as tone, pitch and word choice, that can provide insight into their mental and emotional state. By analyzing these markers, researchers can track changes in mood, cognition and overall well-being over time.
Understanding psilocybin’s effectiveness
The OPTIMIZE study (An Investigation of Strategies to Understand and Optimize the Antidepressant Effects of Psilocybin) is a clinical trial examining whether adding mild, non-invasive electrical stimulation of the vagus nerve might enhance the antidepressant benefits of psilocybin. This is a Phase 2 study of psilocybin, meaning researchers are moving beyond early safety tests and focusing on how well psilocybin works as a treatment for depression.
Fabla will be essential for monitoring how participants’ speech, emotions, and social interactions change before and after treatment. Participants receive personalized questions via the app, allowing researchers to track individual speech patterns over time. This approach not only helps compare each person’s speech to their own baseline but also provides insight into how participants’ experiences change in response to treatment by examining how their language evolves throughout the study.
Recruitment begins in April 2025 for 141 adults experiencing a depressive episode of at least 60 days. All participants receive a single 25 mg dose of psilocybin under controlled conditions, accompanied by preparation sessions and post-dosing integration sessions with trained facilitators. Participants will be monitored over time to measure changes in depression severity, anxiety, well-being, social behavior and overall quality of life.
“The OPTIMIZE study is about more than just testing psilocybin’s effects. It’s about understanding how this treatment changes the way people think, feel, and engage with the world,” says Roman Palitsky, PhD, director of research projects for Emory Spiritual Health and the Emory site principal investigator for the OPTIMIZE study. “Fabla captures those changes in real time, offering a deeper, more nuanced view of the healing process than traditional surveys or laboratory methods.”
Tracking change through speech
Fabla was developed at Emory’s AppHatchery, part of the Georgia Clinical and Translational Science Alliance, a coalition of technology leaders creating patient-centered mobile health care apps.
“Our goal from the start was to create a tool that is both scientifically rigorous and easy to use,” says Santiago Arconada Alvarez, MS, co-director of apps and digital platforms at AppHatchery. “We wanted an app that could seamlessly integrate into research, while giving participants control over their experience. When people feel in charge of how they share their story, it not only strengthens the data but also helps them feel more empowered in their mental health journey.”
The Electronically Activated Recorder (EAR), a precursor to Fabla, has been widely used in psychological research. The EAR is a device that captures brief audio clips of an individual’s environment randomly throughout the day, recording spontaneous speech and background noise. Kaplan played a key role in advancing EAR research during graduate school. Fabla, however, takes a different approach by inviting participants to actively record voice diaries using their mobile phone in response to specific prompts. “Instead of passively collecting speech data, we’re allowing individuals to share their own narratives in real-time,” says Kaplan.
Research suggests that depression can change the way people speak. Individuals with depression often use more self-referential words, such as “I,” “me” and “mine,” and fewer group-related words like “we” and “us.” Their voices may also sound flatter or monotone. Studies show that paying attention to these speech patterns can help researchers understand how severe someone’s depression is and how well they respond to treatment.
Participants in the OPTIMIZE study will use Fabla to document their thoughts and emotions daily for two weeks before their psilocybin treatment and continue to engage with the app for six weeks following their experience. Researchers then analyze what they say and how they say it, paying attention to things like tone, speed and voice changes.
“We know psilocybin can create profound shifts in perception and emotional processing, but understanding how those changes unfold over time, and in daily life, is critical,” Palitsky says. “Fabla allows us to listen — literally — to how participants express themselves before and after treatment. Are they speaking with more hope? Do they have more concentration on others? By studying these shifts in language, we can better understand how psilocybin can help recovery from depression.”
A new way to study psychedelic therapy
Unlike conventional antidepressants, which work gradually by altering brain chemistry over weeks or months, psilocybin appears to bring about rapid and sometimes lasting change. Some individuals describe feeling like their thought patterns have been reset, while others struggle to articulate their experience.
Fabla captures these reflections as they unfold. “It provides real-time insights into how people process their experiences,” Kaplan says. “Rather than simply asking if someone feels ‘better,’ we’re examining how their internal dialogue changes. Fabla lets participants give us a window into the deeply personal nature of a psychedelic experience.”
Alongside Fabla, participants will also wear the EAR device at three different points: before treatment, immediately after and again six weeks later. The EAR passively collects information about participants’ real-world behaviors and conversations, offering a contrast to the self-directed recordings in Fabla. Together, these tools help researchers understand how participants’ internal experiences and their everyday behaviors change over the course of treatment, and whether those changes persist.
Potential beyond clinical research
Fabla’s potential extends beyond research settings. Kaplan envisions a scenario where individuals can use the app as part of therapy, tracking their own progress and sharing key moments with mental health professionals.
“Much of the work in therapy happens outside the therapist’s office,” she says. “This tool allows people to document their reflections in real time, rather than relying on memory during sessions.”
User privacy has been a major consideration in Fabla’s development. Unlike the EAR, which records randomly and automatically, Fabla gives users complete control over when they record. Participants can review, delete and retain full control over their data.
In addition to its role in the OPTIMIZE study, Fabla is being integrated into six other research initiatives, including projects examining physician burnout and stress among frontline health care workers. As artificial intelligence advances, researchers hope to automate aspects of speech analysis, reducing the need for manual data processing.
“We are only beginning to tap into what’s possible,” Kaplan says. “My hope for Fabla is that researchers across the health sciences who are designing studies will use this tool and adopt it for their own aims and purposes.”
Although psilocybin remains a topic of debate, research continues to move forward. As scientists work toward developing new models for mental health care, tools like Fabla could redefine how we measure healing. For now, Emory researchers are listening.
The OPTIMIZE study (NCT06512194) is being conducted by the Vail Health Behavioral Health Innovation Center in Edwards, Colorado, in collaboration with Emory University, the University of Wisconsin-Madison, the University of California San Francisco and UCLA. Funding for the study has been provided by the Tiny Blue Dot Foundation and philanthropic support through the Vail Health Foundation.