Common questions

Underlay.fm is a focus audio app that layers ambient soundscapes based on what you're doing and how you're feeling. Before each session, you choose a work mode: deep focus, reading, creative thinking, journaling, or light work, and a mood state: scattered, anxious, steady, tired, or wired. It uses that combination to shape layered audio engineered for that exact cognitive moment.

No. Deliberately not. There are no melodies, chord progressions, lyrics, or rhythmic structure. Underlay.fm layers pre-produced ambient stems: drones, tonal textures, phase elements, sub-harmonic grounding, then mixes and modulates them live in your browser (Web Audio) so the blend, volume, and tone shift continuously through a session rather than looping a static track. The goal is to give your ears enough to settle on without competing with whatever you're actually trying to think about. If you've ever caught yourself humming along to a "focus playlist" mid-paragraph, you know the problem.

Binaural beats happen when each ear hears a slightly different frequency. The brain perceives a third tone at the difference between them. Research links specific frequencies to different mental states: theta (4–8 Hz) for creative thinking, alpha (8–13 Hz) for relaxed focus, beta (13–30 Hz) for active concentration. Underlay.fm embeds them into every Pro session, tuned to your work mode and mood.

Headphones are strongly recommended. Binaural beats only work when each ear receives a separate frequency signal; speakers physically blend the channels, eliminating the effect. The ambient soundscapes still work through speakers, but Pro subscribers get the full binaural benefit only with headphones or earbuds. Any stereo headphones work; expensive audiophile gear is not required.

Before every session, Underlay.fm asks two questions: what are you working on, and how are you feeling right now? The mood state isn't just metadata, it changes the actual audio. Someone who is anxious draws a warmer, darker sound palette (velvet and haze textures) tuned toward calming alpha frequencies. Someone who is tired gets bright, crystalline layers biased toward alerting beta. The same work mode (say, deep focus) sounds and feels different depending on your current state, and the environment preview on the setup screen shows you exactly what changed before you press play.

The two layer independently. Work mode sets the baseline: deep focus and light work stay in a brighter, alert range, reading settles into calm alpha, creative thinking and journaling drop into slower theta for open, reflective thinking. Mood then reshapes that baseline: scattered locks it dark and static, anxious adds a slow descending drift, tired brightens the mix, wired gets oscillating texture.

Lo-fi and focus playlists are curated music: someone chose songs they thought sounded "studious." They still contain melodies, instruments, and emotional arcs your brain can't fully ignore. Underlay.fm generates no music at all. It layers ambient stems in real time, calibrated to your mood and task, with nothing to skip, shuffle, or accidentally start humming.

Underlay.fm supports five work modes: Deep Focus (demanding analytical or coding tasks), Light Work (email, admin, low-stakes tasks), Reading (dense material comprehension), Creative Thinking (open-ended ideation and brainstorming), and Journaling (reflective writing and introspection). Each mode maps to different ambient textures and binaural beat target frequencies.

Yes. The free plan includes one session per day, up to 45 minutes each, across all work modes, no credit card required. You can try it without creating an account. Pro plans start at $7.99/month and unlock unlimited sessions (up to 8 hours each), binaural beats, Pomodoro cycles with automatic breaks, custom durations, and mood-tagged session history with focus stats.

Underlay.fm works on any device with a modern web browser (desktop, laptop, tablet, and mobile). It can be installed as a Progressive Web App (PWA) on iOS via Safari (Share → Add to Home Screen) and Android via Chrome (Install App) for a native-feeling experience without an app store download.

Once the app has loaded and a session has been started at least once, the audio stems cache locally via the PWA service worker. Subsequent sessions work even with an unreliable or absent internet connection.

It depends on your work style and cognitive load. Underlay.fm supports sessions from a few minutes up to 8 hours (Pro). For most knowledge workers, 25–90 minute blocks work well. Pomodoro mode (Pro) structures sessions automatically: 25 minutes of focus followed by a 5-minute break, cycling until you stop.

Whether you click "End Session" or let the timer run out, Underlay.fm plays a soft gong to signal the transition, then fades the audio over several seconds. You'll see a "Session Complete" screen showing your total focused time. There are no abrupt cuts or jarring interruptions.

Underlay.fm is built for focus, not relaxation or sleep. The frequencies are tuned to keep you alert and working. The lowest range it uses (theta, ~6 Hz) is meditative but still alerting compared to true sleep audio (delta, 0.5–4 Hz). For sleep you'd want something built specifically for that.

Many people with ADHD find Underlay.fm easier to stay with than music-based focus tools. The reason is structural: music, even AI-generated functional music, contains melodies and rhythmic patterns that the brain tracks involuntarily. For ADHD brains already fighting for attentional control, that background processing competes with the task at hand. It generates no music at all, so there's nothing to hum along to or get distracted by. The other factor is variability. ADHD presents differently day to day: some days you're scattered, some days anxious, some days oddly wired. Underlay.fm asks how you're feeling before every session and adapts the audio to that specific state, rather than defaulting to a generic "Focus" mode regardless of where you actually are. Note: it is not a medical tool and makes no clinical claims about ADHD treatment.

Yes. Every session has live controls for volume, warmth (how bright or dark the overall tone is), and depth (how prominent the low-end bed and sub layers are). You can also toggle individual sound layers on or off (bed, mid, air, sub, and phase) to shape the texture however you like. The difference from a manual mixer like Noisli is that Underlay.fm starts from a soundscape already engineered for your mood and work mode. You're adjusting something calibrated to your current state, not building from silence.

Brain.fm uses AI-generated functional music. It still has musical structure. Endel generates soundscapes that adapt passively to time of day, weather, and biometrics. Underlay.fm doesn't use music at all, and it asks how you're feeling before every session rather than trying to infer it. See the full comparison page for a detailed breakdown.