Why is there a background sound?


I’m recording an audiobook and I have the latest version of Audacity downloaded. There is a background hiss/noise that I can’t get rid of on the attached file. I don’t think this is a completely raw file, but I think I at least removed whatever noise reduction has been made. The attached file passes ACX check, which is weird since it has a distinct background noise. Can someone tell me how to fix the attached file?

I’m recording an audiobook… I don’t think this is a completely raw file

I don’t think so either but you should know since it’s your recording. :wink: The voice sounds “artificial”… Maybe too much noise reduction or other processing.

but I think I at least removed whatever noise reduction has been made. The attached file passes ACX check

When I ran ACX Check it failed noise…

which is weird since it has a distinct background noise.

That is “weird” I can’t say where it came from. It probably sounds weird because of the processing/noise reduction.

Can someone tell me how to fix the attached file?

I didn’t try to fix it but it’s always best to prevent noise. Please tell us about your equipment/setup.

Not everything can be "fixed’.

You’ll get acoustic room noise and although there are some “tricks” to minimize it it’s almost always going to be an issue unless you’re recording in a soundproof studio.

The preamp (built-into your soundcard, interface, or USB microphone) will always generate some internal white noise. Better equipment will generate less noise.

Sometimes, high-pitch “switching noise” gets into the preamp from the computer’s power supply. That can happen with a USB powered interface. (An audio interface with it’s own power supply will be immune to any electrical noise from the computer.)

You can get power line hum (into the microphone/preamp through electro-magnetic radiation or from the power supply.

With a quiet room, good equipment, good mic position, etc., you can usually bring the recording into spec with some gentle noise reduction without over-damaging the sound quality.

We can’t work on or evaluate a sound sample with any processing in it. We can’t take processing out of a file.

Try creating a fresh new sound file according to these instructions.


Read down the blue links. They’re very short.

Don’t change anything. Shoot it, export it and post it.


You might forward your microphone name, type of computer, etc.

Sometimes, as DVDDoug above, some microphones have standard problems and we have pre-baked solutions.


Thanks for all the responses. I think it may be my heater that goes on—and stays on for several minutes—that’s causing that annoying hiss. Plus, me messing with the recording:)

Anyway, what do you think of this sample with no hiss that I’m attaching? It passes ACX Check. Does it sound artificial/bad as well?

I’ve also uploaded a raw sound file like you suggested. What do you think?

Two problems, one technical and one theater.

There is a very loud motor or other sound in the background. It’s too loud to filter out with Noise Reduction because it will cause voice damage if you try. There is a fuzzy rule that if you can tell your computer, air conditioning or heater is on just by listening, it’s too loud.

But there’s another problem. You’re announcing in a large bare room, right? I can hear your voice echoes coming back from the walls. It’s the announcing in a kitchen or bathroom effect. The first problem will fail the ACX Robot Inspector and the second will fail ACX Human Quality Control.

It’s not unusual for people to have to announce around motors or neighborhood sounds. I have to wait until after about 10PM to get rid of enough street noises.

You can make a Kitchen Table Studio and take care of the room reverb and echoes.



Thank you, Koz. Just so I’m sure what you’re referring to with the two problems, technical and theater. Is that in reference to my raw sound test or the chapter 8 one?

I record in my living room and have lots of pillows/curtains around me (like a foot away). But it might not be enough then.

Need to be cocooned in cushions/quilts (or similar), see … https://youtu.be/5Se381sERrY?t=142

Got it. Did this forum voice test in my closet. Better?

Is that in reference to my raw sound test

Yes.You can’t fix echoes in Audacity software. So even if you did manage to suppress enough of the heater noise, you’d still be left with announcing in a kitchen sound.

This is a common curse. Nobody reading at home passes noise. The microphone makers insist you can set up on the kitchen table, read a book, make a fortune and retire to a nice vacation home in Boca. There’s a little more to it than that.


Dueling posts. Two posts arrived at the same time. Reading…


The raw closet test reading will not pass noise, but it’s much closer. I applied 9, 6, 6 noise reduction and I got the ACX Check posted here.

Screen Shot 2020-02-25 at 18.51.33.png
It does pass noise, but not by enough. The limit is -60dB. Your Closet Test with Noise Reduction is -63dB (quieter), but not enough. If you do anything at all wrong, you will fail and there’s nothing worse than failing some chapters and not others.

I applied 12, 6, 6 and pass the noise test at -65dB (just enough). That’s it. You can’t go any higher reduction without making your voice sound funny.

Any chance at all of getting rid of more room noise? Could that be your computer fan sound? As you struggle with this, Do Not block any computer ventilation or cooling.


I don’t think that my computer fan. I have a MacBook Air. Laptop. Does it have a fan? I’m sitting with a chair in my closet. In other words, I’m sitting right outside my closet with my face and knees in (its small). Maybe I can get one of those really thick moving blankets and hang it so that it covers my back and sides? I would basically be in a cocoon then.

I could also move a rolling coat rack and put it behind me, but then it would still be open over my head. What’s the better option?

You never said what your microphone was. Does it have a volume control on it? That setting should probably be higher. Your raw annoucning is very low volume. If you make it too low, the electronic noise of the microphone will start to interfere with your voice. Your voice recording blue waves should look more like the right side of this pix.

Screen Shot 2020-02-25 at 19.37.22.png

have a MacBook Air.

So do I. It does have a fan, but it only comes on loud when the Air is stressed or is trying to do a lot of work.

What’s the microphone?


Oh. Wait. We may have a different problem. You didn’t leave the two seconds of dead silence at the front of your voice track. That can throw off the tools.

Read Closet-Two.


I have an audio-tecnicha 2020 usb plus. I just did another voice test that I’m attaching. The noise is 69 when I do the ACX test. I cut out a lot of dead air in the beginning, leaving only like a second. So you’re saying the MIC volume control should be up to max loud then? I have it in the middle.

I see that I can raise the volume for the mic in the Audacity program. I did that and recorded a little. Much bigger waves now.

Quite a bit of noise reduction required to pass ACX …

There will be a sweet-spot* on the mic volume control where the signal-to-noise ratio is optimum.
(* found via trial & error).

The free version of the “couture” expander plugin can push-down the noise-floor a little bit,
particularly when you are not speaking.

This is your microphone, right?

Screen Shot 2020-02-26 at 2.39.37.png
It doesn’t have any voice volume controls. The adjustments on the microphone are both for headphone mixing and don’t affect the show.

Here’s how we’re doing this: Open your sample in Audacity. Apply the three audiobook mastering tools and then ACX Check.

Screen Shot 2020-02-15 at 4.16.02.png
That gives you the performance as it would be sent to ACX. It passes Peak and RMS (Loudness), but that noise level is -51dB, far louder than the -65dB goal.

I swear it’s mostly motor noise. Do you have your microphone sitting on a table or bench? Can you try the book and towel method?

That will help with noises and vibration coming up to the table from the floor. That can be a problem if you live in a multi-story apartment or close to the heaters or air conditioners and they’re actually shaking the room.

I can force your last post to clear but this is how I did it (this is an abbreviation).

Notch Filter 99
Notch filter 119
Filter Curve
RMS Normalize
Noise Reduction 6, 6, 6

The first two notches are to get rid of most of the motor noise rumble. They can also affect your voice, so it would be good if I didn’t need them. The next three tools are Audiobook Mastering. That still doesn’t pass, so gentle Noise Reduction is used to mop up anything left.

Screen Shot 2020-02-26 at 3.29.48.png
I’m not sure where to go with this. You seem to be trying to read in an aggressively hostile—noisy environment.

Just a note that after you master the actual recording, you also have to pass the vocal quality and theater tests. ACX Tests everything. Why would somebody go to hear you read in real life—without the audiobook in the middle?