How the online voice recorder works
The recorder uses two features built into every modern browser. getUserMedia asks for permission and opens your microphone. MediaRecorder compresses the sound as you speak, usually with the Opus codec in Chrome, Edge and Firefox, or AAC in Safari. While you record, the Web Audio API measures the loudness of the incoming sound many times a second to drive the level meter.
When you stop, the recording is kept in the page as a file you can play back and download. Converting to WAV decodes it and writes raw 16-bit samples. Converting to MP3 decodes it and encodes it with the LAME MP3 encoder, compiled to WebAssembly so it runs in the page. At no point is any audio sent to a server.
Reading the level meter
The meter shows the loudness of your voice in decibels relative to the loudest sound the recording can hold (dBFS). 0 dBFS is the ceiling; anything louder is clipped and sounds harsh and distorted.
RMS (root mean square) is the average strength of the sound wave over a short window. Some reference points:
| Meter | Level | What to do |
|---|---|---|
| Red end | above −3 dBFS | Too loud: move back or lower the input volume |
| Amber | −12 to −3 dBFS | Loud; fine for short peaks |
| Green, middle | −40 to −12 dBFS | Good speaking level |
| Nearly empty | below −45 dBFS | Too quiet: move closer |
A sound at half the maximum strength reads about −6 dBFS; a tenth of the maximum reads −20 dBFS.
How much space does a recording take?
The browser records compressed audio at about 128 kbps, so:
A 10-minute interview is about 10 MB as the original file or as an MP3 at 128 kbps. As WAV it is much bigger: 48,000 samples × 2 bytes × 600 seconds = 57.6 MB for mono, and twice that if your microphone records in stereo. Use WAV only if an editing program or transcription service asks for it.
Tips for a clean recording
- Distance: keep the microphone a hand’s width (about 15–20 cm) from your mouth, slightly to the side to avoid popping “p” and “b” sounds.
- Room: soft furnishings absorb echo. A wardrobe full of clothes makes a surprisingly good booth.
- Noise reduction: leave Reduce background noise and echo on for speech. Turn it off for music, where it can make instruments sound thin or pump in volume.
- Choose the right microphone. After you allow access, a list of microphones appears if you have more than one, such as a headset and a laptop mic.
- Pause instead of stopping to keep one file, or stop to make separate takes. Every take stays listed until you close the page.
After recording
- Cut silence at the start and end, or add a fade, with the Audio Trimmer.
- Change format or bitrate with the Audio Converter.
- Recording a tutorial? The Screen Recorder captures your screen with your voice.
Browser support and permissions
The recorder works in Chrome, Edge, Firefox, Opera and Safari 14.1 or newer, on computers and phones. It needs a secure (https) page, which this is. If access is blocked, click the lock or microphone icon beside the address bar and allow the microphone. Browsers built into social media apps often block microphones entirely; open the page in Safari or Chrome instead.