Play a slow logarithmic sweep and hear every rattle in the room
Processed in your browser. Nothing is uploaded. Updated on 24 Oct 2026.Rattles announce themselves during a slow sweep and stay hidden the rest of the time: a loose grille, a bookshelf, a coin on the desk or a panel in the laptop lid starts buzzing on one note and stops on the next. Choose a thirty second sweep, sit still, and listen rather than watching the chart. Anything that joins in has just told you where it is.
Sweep length is already set to 15 seconds; pick 4, 8 or 30 seconds instead if you want.
Allow the microphone to draw a curve, or press run the sweep without the microphone to listen only.
Press Run the sweep; the frequency it has reached shows in Hz as it climbs.
Listen for rattles as it passes each note, and press Stop or Escape to end it early.
This tool plays a slow logarithmic sweep from 20 Hz to 20 kHz through your speakers, records it back through your microphone, and draws what survived the journey as a curve in third-octave bands, relative to 1 kHz.
What the measurement is genuinely good for is comparison. Run it twice in the same place with two different speakers and the difference between the curves is real, because the microphone and the room were the same both times. It is also good at finding the point where a device stops producing bass at all, at showing a broad treble roll-off, and at catching a rattle.
Frequency runs left to right on a logarithmic axis, so each octave takes the same width, which is how hearing works. The curve is normalised so 1 kHz sits at 0 dB. The tool reports the points where the response last stands within 3 dB and within 10 dB of the middle of the curve, and the slope above 5 kHz in decibels per octave.
The rest of the article, and all 6 questions about Frequency Response Sweep, are on the Frequency Response Sweep page.
Small drivers cannot move enough air to produce low frequencies, so a typical laptop speaker is already falling away by 200 Hz and has almost nothing left below 150. Phones are usually worse. The bass you hear in music on those speakers comes from harmonics higher up rather than from the fundamental.
Not by chart, because the sound never reaches the microphone. Use the sweep by ear instead: note where the bass turns into a faint rumble and where the treble vanishes, then compare those two points between one pair and another. Judging headphones that way is more useful than most published specifications.
A logarithmic sweep spends the same amount of time in every octave, so 20 to 40 Hz takes as long as 10 to 20 kHz. Hearing and audio measurement both work that way, which means every part of the range gets an equal number of readings rather than the treble getting almost all of them.
No. Levels are read frame by frame while the sweep plays and only the resulting curve is kept, which is a few dozen numbers. No audio buffer is stored, no file is written, and nothing is uploaded. Stopping the sweep releases the microphone immediately.
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Same job, other tools: Sweep Tone Generator – Sweep smoothly between two frequencies over a time you choose · Frequency Generator – Generate a steady test frequency for speakers, headphones or instruments · Speed Up Audio – Make audio faster or slower without the chipmunk voice · High Frequency Hearing Check – Screen the top tones, 4 kHz and 8 kHz, ear by ear, then test higher with a tone generator · Play Audio Backwards – Hear a recording backwards, then forwards, for the reverse singing challenge · Increase Audio Volume – Raise a quiet recording as far as it will go before anything starts to distort.
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