Can you give me some direction on this raw audio file?

I have been working to reduce noise in my recording closet the last couple of weeks. I have recorded a short sample reading. I have done no editing to it. Does the space seem quiet enough? And do I need to change any setting on my usb or mic to get a better raw sound before moving to the next step editing in Audacity.

I am recording using an Audio Technica AT4040, The file is recorded via Twisted Wave to an iphone and then sent via drop box to Audacity for the next step. I am using a Focusrite Itrack Solo USB because it allows direct recording to an iphone or Ipad and my lap top sounds like a bunch of tiny tanks and is just way too loud.

Once I am in the position of getting a good raw sound what are my next steps? I am assuming that I edit out coughs, breaths, mistakes and so forth by either deleting the section or pasting some a bit of silence recorded at the start of the track. But I don’t know where to go from there.

In terms of noise level I think you are in great shape. That is a very quiet recording.

There is a bit of a hollow timbre to your voice however which might be due to reflections from the walls of your “studio”. Is your closet just bare walls, or have you made any attempt to dampen the sound with foam or just leaving the coats hanging on the ends?

My poor man’s sound treatment is as follows:

throw rug on the floor. Dense 1/2’ exercise mat on top of that. Another throw rug on top of that

Walls 1/2" exercise mats screwed to the walls. Old comforter screwed to the walls around the top. No screws in the middle of the wall. the comforter hangs loose from the top attachment points.

Steel insulated exterior door to get in and out-used because I had one that I had taken out when when I renovated my house and it was still good. I have a cord that goes in front of the door and I have a flannel sheet on that that I slide over when I recorded.

There is no room to hang any clothes. This is a coat closet measures 48" by 28" There is a half circle window at the top and I have a light hanging on the outside of the door because it makes it too hot too quickly with the light inside. I have a chair in there, a mic stand, metal folding music stand that i put cardboard on top and covered in cloth. I have to straddle the music and mic stand. And I have a little narrow table that is 8" wide to set a drink on in front of me and on the other side of the music stand and mic set up. And there is a tiny shelf on the wall to set the USB so I can see if the light is red or green when I talk.

Well certainly sounds like you’ve covered the reflections issue. What I’m hearing may well just be your voice.

The exercise mats are probably less than ideal as their solid smooth surface will still reflect to some extent (but nowhere near as badly as a bare plaster wall) – you might try a cheap throw rug over the exercise mat on the wall you are facing when you record. No need to cover the entire wall, just he area immediately in front of you. Slipping something behind the mats so that they bow with a bit of a curve instead of being totally flat may make a difference as well. Don’t worry about the screw heads, they are too small to reflect any significant energy.

Your recording is so quiet I’m not sure I believe that is isn’t processed in some way. Is that .wav file what was output by Twisted Wave? Are you recording at 24bit?

I’m sure Koz and the others will chime in soon with their own take.

I have a comforter over the mats. I have done no processing because frankly I don’t know how yet. As I was talking this through with another friend, it occurred to me that the shelving board above my head is exposed. I am going to sacrifice a blanket and staple it up there. I have been reading threads here from others in the past and that led me to take more time over the last couple of weeks to back up and stop recording and treat the best as best as I can. I read a thread about a couple of people with full audio books that got rejected due to noise. I decided to stop recording and treat the noise to the best of my ability first.

I am also going to put more material on the slide rope hang line in front of the door since I used a thin flannel sheet there.

This was recorded in twisted wave 44100 16 mono. I don’t know how to change any other settings in that program. It is the app version for iphone and ipad. I am not going to use that to edit. I want to do all that in audacity.

Hello again! Just want to follow this.

Oh and I also got my house warm and then shut off the heating system while I recorded. Someone else told me to do that. They said you can either struggle to remove the noise or just don’t record it in the first place. This closet is also in the center of my house with no exterior walls.

I think some kind of comb-filtering is going on, causing that hollowness, as can be seen in spectrogram view with window size of about 4096. Many pale lines cutting horizontally. Suggests hard parallel surfaces needing better treatment.

Ok, I did some additional treatments to the walls and the bottom of the shelving above my head. Does that help with the sound at all? I still have not run any filters. This is the raw wave file

Any improvement or does it still sound the same to you guys?

“Treatment” can be just making them non-parallel. We had a remarkably good room to record in once, not because of extensive blankets and duvets and carpets, but because none of the walls were parallel. Will will correct me, but I don’t think the ceiling was parallel to the floor, either. Many sound recordings were made in that room.

Don’t forget to put something between the microphone and the desk if you have a desk stand. That’s a favorite place to cause an odd sounding voice.

Forget all the complicated microphones in this picture. Look at the folded furniture moving blanket on the desk.

They were perfectly correct. You can spend hours in Audacity trying to patch together a ratty recording only to get a different ratty recording. Don’t believe the phrase “Noise Removal,” and we can’t take out echoes.


One more. If you do have a desk stand, start a recording with you talking and slowly pick the microphone straight up. If your voice goes through ‘talking in a wine glass’ effects, then you have a “live” table and need more towels. If your voice just gets quieter, that’s normal.


That’s pretty impressive. You will probably pass ACX compliance without a great deal of work although the sound is still a little “tight.” I could listen to a story in that voice.

Here’s a trick. Steve designed a “rumble filter” which you can use installed in Effect > Equalization. It will give you a significantly quieter “background” with little or no effect on the voice.


Steve Daulton created a custom equalization curve for the purpose of helping voice presentations pass Audiobook Certification. It’s action is to eliminate rumble and low pitched sounds, suppress power line hum, and suppress P-popping and other thumpy mouth sounds. It can help with hand-held microphone rumbly sounds.

Take questions to the Audacity forum.\

— Get the custom filter.

The filter name is LF_rolloff_for_speech.xml. You can download it from here:\

It’s a dead simple XML text file. You can open it in TextEdit or Notepad and read it. Be careful not to change the filename or extension.

— Add a Custom Curve to the Audacity Equalization Tool.

Put something on the timeline even if you have to generate a couple of seconds of silence or noise. Content doesn’t matter.

Effect > Equalization… > Save/Manage Curves > Import > LF_rolloff_for_speech.xml. OK.

— Apply the curve.

Effect > Equalization > Select Curve > LF rolloff for speech. Length of filter greater than 8000. OK.



Thanks for the feedback.

One very common problem is the inability to get background noise, overall loudness and peak blue waves at the same time. They complain that overall loudness (RMS) is too low. You know how to set peaks. That’s dead simple Effect > Amplify or Normalize. RMS is a little more of a challenge. You need one of the compressor effects. Maybe not very much, just enough to get past the specification.

But wait (you say in horror), now that the loudness and peaks are in the right place, the background hiss or room environment sound is too loud. That was just on the edge before, but the compressor has pushed it up too far.

That’s where Steve’s filter may be handy. I can get an easy 10dB reduction in background noises for you with the application of that filter. Your presentation happens to have an abundance of low pitched tones (goodness knows from where) and that can ruin a noise test — even though you can’t hear them.

Dump them.


There is something wobbling near 10Hz, which is inaudible but best filtered out with a simple highpass or with that equalization curve.

I get this sort of thing too, and my suspicion is my pop filter on its gooseneck.

There is something wobbling near 10Hz,

That happens a lot and it’s dead easy to get rid of with Steve’s filter.

I do wonder where it’s coming from. It’s too common to be a particular microphone mount. It’s like everybody’s recording in a earthquake zone. It goes up as you go down in frequency, too, which is most unusual.

I wonder if it’s a cousin to the frying mosquitoes problem. High frequency (non-active) filters do a grand job on that, but let low frequency noises sail through.


Well there was some obvious bumping of the microphone at the start and end of the second sample, which I am sure we all know about, but I notice that wobble also gets much higher in amplitude as part of that and took a little longer to decay than the audible part of the bump. So it might not be seismic, it might have its source really close to the mic.

Paul, you make an interesting point. The arm on my pop filter is one of those metal coiled things that you are supposed to be able to bend and it stand in place. Only it doesn’t. So I put it where it where it was supposed to go and then put a loop of elastic shock cord from the filter neck over to the mic and the tension holds in in place. I wonder if that is creating some vibration. It is heavy cord that is 1/8"