Before you record

Test your recording space in ten seconds

Most audiobook rejections that software cannot fix are rejections of a room, not of a take. This measures your room and then your voice in it, and says whether the gap is wide enough for a chapter that will pass — before you spend a weekend recording one.

  • Nothing is recorded
  • Ten seconds, two phases
  • The same rule the fixer refuses on

Measure this room

Your browser will ask for the microphone. Samples are turned into running numbers and thrown away as they arrive — nothing is stored, and nothing is sent anywhere.

  1. Five seconds of quiet. Sit still and let the room be the only thing making noise.
  2. Five seconds reading. A sentence appears; read it at the volume you would narrate.

Why two phases

One number cannot diagnose a room

The floor alone means little

A room at −55 dBFS is fine for a loud, close microphone and hopeless for a quiet one two feet away, because what matters is the distance between your voice and the room, not either number by itself. That is why this test measures both and reports the separation.

Thirty decibels is where software gives up

Below roughly 30 dB of separation, no amount of gain staging or noise reduction produces a clean chapter: lifting the voice lifts the room with it, and pulling the gaps down makes the recording breathe audibly. The chapter fixer can still subtract a measured noise spectrum from under the voice and rescues a file down to about 18 dB, but that is a repair; this page lets you find out before the recording whether you will need one.

Gain is not free

Recording quietly and turning it up later moves the room up by the same decibels. The verdict here does that arithmetic for you: it takes the gain your voice would need to reach ACX’s window and reports where your floor lands afterwards.

The browser is asked to stay out of the way

Echo cancellation, noise suppression and automatic gain are all switched off in the request, because each one would change the thing being measured. If a browser or operating system insists on its own processing anyway, a room can measure quieter here than it will in your interface.

Deliberately modest

What this test is not

  • Not a substitute for checking a real chapter — a room test cannot hear plosives, mouth noise or reverb
  • Not calibrated in SPL: dBFS here is relative to your microphone’s current gain, which is the number that matters for a recording made at that gain
  • Not a promise: passing here means the room is capable, not that a chapter recorded in it will pass

Once you have recorded something, measure the file itself in the chapter checker — and if a whole book is already recorded, the batch checker compares every chapter against the book.

Straight answers

Questions about testing a recording space

How do I test my room for recording an audiobook?

Press start and allow the microphone. Stay quiet for five seconds while the page measures the room, then read the sentence that appears for five seconds at the volume you would narrate. You get the room's floor, your level, the separation between them, and where the floor lands after the gain ACX's window needs.

What noise floor do I need for ACX?

ACX asks for a noise floor of −60 dB RMS or lower. In a room, what decides it is the distance between your voice and the floor: recording quietly and adding gain later lifts the floor by the same amount, so this test does that arithmetic for you.

Why does the test want 30 dB of separation?

Below roughly 30 dB, pulling down the gaps between words is not enough and the recording starts to breathe audibly. The chapter fixer can still subtract a measured noise spectrum from under the voice and rescues files down to about 18 dB, but that is a repair; a room that clears 30 dB needs none.

Why does it switch off noise suppression?

Echo cancellation, noise suppression and automatic gain are all switched off in the request, because each would change the thing being measured. If a browser or operating system insists on its own processing anyway, a room can measure quieter here than it does in your interface.

Is anything recorded?

No. The samples become running numbers as they arrive and are discarded, so nothing is recorded, stored or uploaded.