Live Morse Code Audio Decoder

Live Morse Code Decoder from Microphone — Real-Time Audio Copy

Copying Morse code by ear is the skill every operator aspires to master. Our live audio Morse decoder listens through your device microphone, detects dot and dash tones in real time, and displays the pattern as text — turning any CW source into readable Morse without a hardware decoder.

Play Morse from our translator, a practice app, a shortwave radio speaker, or even tap rhythm on a desk near the mic. The decoder calibrates to your room, filters background noise, and syncs detected patterns to the translator below for instant plain-text decoding.

What Is Live Morse Audio Decoding?

Traditional Morse copying requires a trained ear to distinguish short tones (dots) from long tones (dashes) and recognize letter and word gaps. Software decoders automate this by analyzing audio frequency and amplitude over time. Our browser-based decoder uses the Web Audio API to sample microphone input, identify tone bursts in the CW frequency range, and classify each burst by duration.

Short bursts below the dash threshold become dots. Longer bursts become dashes. Pauses between bursts trigger letter spaces; longer pauses insert word separators. The result appears live in the detection panel and syncs to the Morse-to-text translator on page load completion or when you stop listening.

How Our Microphone Decoder Works

Calibration Phase

When you click Start Listening, the decoder captures a brief sample of ambient room noise. This baseline sets the detection threshold so fans, HVAC hum, and computer noise do not register as Morse tones. Stay quiet during calibration for best results.

Hybrid RMS + Frequency Detection

The analyzer combines two signals: root-mean-square (RMS) amplitude to detect when any tone is present, and frequency analysis to confirm the tone falls within the 350–1400 Hz range typical of CW radio and practice oscillators. Tones outside this range are ignored as non-Morse noise.

Duration Classification

Once a tone starts, the decoder measures its length. Duration compared against the expected dot length at your selected WPM determines dot versus dash classification. The formula matches our audio player: dot length = 1.2 ÷ WPM seconds.

Gap Detection and Sync

Silence between tones is measured against letter-gap and word-gap thresholds. When a letter completes, the pattern syncs to the translator below via a custom event. On stop, the full message transfers for plain-text decoding and copy.

Step-by-Step: Decode Morse from Audio

1. Click Start Listening and allow microphone access when your browser prompts.
2. Wait for calibration — remain silent for two to three seconds while the signal meter stabilizes.
3. Set Expected WPM to match your source. If playing SOS from our translator at 15 WPM, set the slider to 15.
4. Adjust Sensitivity — raise if tones are missed; lower if background noise triggers false dots.
5. Play or send Morse through a speaker near the mic, or use the Play button on the translator below.
6. Read results in the live panel and decoded text below. Click Stop when finished.

Controls Explained

Practice Scenarios That Work Well

• Self-practice loop — enter text in the translator below, press Play, and decode through the mic above
• Two-device setup — play CW from a phone speaker while the decoder runs on your laptop
• Ham radio monitoring — place the mic near a receiver speaker during slow CW nets (5–15 WPM)
• Classroom demos — teacher plays tones; students watch real-time decoding on a projector
• Tap rhythm practice — tap dots and dashes on a desk; the mic picks up mechanical rhythm

Common Live Decoding Problems

Too Many False Dots from Background Noise

Lower the Sensitivity slider and re-start listening. Move away from fans, air conditioners, and open windows. Re-calibrate in a quieter moment.

Missing Dashes or Whole Letters

Increase Sensitivity or move the speaker closer to the mic. Confirm Expected WPM matches the source — a 20 WPM signal decoded at 10 WPM misclassifies dash lengths.

Browser Blocks Microphone

Check site permissions in browser settings. HTTPS (or localhost) is required for microphone access. Reload the page after granting permission.

Bluetooth Latency

Wireless headphones and speakers introduce delay that can affect gap detection. Use wired speakers or the built-in laptop speaker for practice.

Privacy and Security

Microphone audio is processed entirely in your browser via the Web Audio API. No audio is recorded, stored, or transmitted to our servers. When you stop listening, the audio context closes and microphone access ends.

This local-only architecture means you can practice with sensitive call signs, exam preparation phrases, or personal messages without data leaving your device. We never use pop-up ads that might interfere with microphone permissions or audio playback.

Building Real Copying Skill

Software decoding is a learning aid, not a replacement for ear training. Use this tool to verify what you hear, not to skip the listening step. The recommended progression:

1. Listen to a message on our Audio Player without looking at text.
2. Write down or speak the letters you recognize.
3. Run the live decoder to check your copy against the detected pattern.
4. Review mistakes and replay at the same speed until accuracy improves.
5. Increase WPM by 2–3 when you consistently copy 90% or more.

Consistent daily practice — even ten minutes — builds the neural pathways for automatic Morse recognition faster than occasional long sessions.

Related Tools

• Morse Code Audio — generate CW tones to decode here
• Morse to Text — decode synced patterns to plain text
• Decode Image — extract Morse from photos
• Text to Morse — create practice messages
• Learning Guide — structured ear-training curriculum