Lemon Lens: Voice Monitor

Lemon Lens is a real-time voice monitor. We can't call it a lie detector, but it's the closest thing to one. Tap the big red button and watch how each voice in the room changes as the conversation goes on.

LIVE VOICE-CHANGE METER
- A 0-10 meter shows how far the voice that is speaking has moved from that same voice's normal
- It learns each voice from its first few lines, then compares pitch, pitch swing, volume, pace and the pause before answering
- Tells you why it moved: "pitch up 5.9 · pace down 2.4"
- Finds two voices on its own (lower and higher) and compares each one only with itself

LIVE GRAPH
- The last 60 seconds of pitch for each voice, with that voice's usual range shaded
- A loudness strip underneath
- Flag markers where a voice shifted

FLAGS
- A running list of the moments worth another listen, with the time and the reason

RECORD, SAVE, SHARE
- Big red record button with a timer and mic level
- Recordings and a notes file save to Downloads/Lemon Lens
- Share a recording to your computer, email or cloud storage in one tap
- Open the recording in The Lemon Lens desktop app for a full transcript and report

YOUR LOOK
- Three themes (Lemon, Studio, Counsel), three layouts (Classic, Control Room, Focus), light and dark mode

PRIVATE BY DESIGN
- No account, no ads, no analytics, no internet connection
- Nothing leaves your phone unless you tap Share

IMPORTANT
We can't call Lemon Lens a lie detector, because no app can tell for certain whether someone is telling the truth. But it's the closest thing to one: it shows you the moments a voice changes. Stress, excitement, anger, emphasis and a bad line all move the meter. Use it to decide where to listen again or what to ask next.
Phones do not let apps hear the audio of a phone call, so Lemon Lens records what the microphone hears: people in the room, or a call on speakerphone.
Some places, including California, require everyone in a conversation to agree before it is recorded. The app asks you to confirm this each time.