Pulsing sound in my recordings

Occasionally (and it’s happening more and more) I hear rapid pulsing sound in the spaces of my VO recordings. I can see the pulsing in the input meter. You can’t hear it as much when my voice is present, though I know that it is there. What is causing this? I have tried closing and restarting the program and sometimes that works but I would love to know what is causing this. I’m doing a lot of self-submitting on Voice123.com and also on ACX and it is becoming a problem. Thank you for any insight you can give me.

I would love to know what is causing this.

We would love to know how you’re recording the show. Which microphone and how is it connected? Include model numbers. We live on fine details.

Which computer and which three-number Audacity?

You might be able to “patch” your existing recordings with the LF-Rolloff filter Steve wrote. It’s a plug-in to Effect > Equalizer and it will peel off any rumble or low pitch throbbing.

Obviously you should try to fix this even if the patch works. You can get the plugin from me.


Adding Audacity Equalization Curves
– Select something on the timeline.
– Effect > Equalization > Save/Manage Curves > Import
– Select LF_rolloff_for_speech.xml > OK. (it won’t open the ZIP. You have to decompress it)
– LF rolloff for speech now appears in the equalization preset curve list.

After you get it installed, select a performance and Effect > Equalization: LF-Rolloff. If you have an odd “Length” slider setting, use about 5000 (mid) > OK.

This is our version of the classic “100Hz Vocal High Pass” filter. Unless you have a terrifically low voice, you won’t notice any vocal change, but most sub-sonic trash should vanish.


I have an HP desktop computer (specs: Intel Core i7-6700T CPU@2,8 GHz, 8.00 GB RAM, 64-bit Operating System)
I am using a Rode NT1-A Cardioid Condenser Microphone with a USB connection. I also use a Blu Snowball and I don’t seem to have the issues with that mic but the input is really low and I don’t know how to properly set my RMS and volume and limiter and condenser settings (and I really want to know - like how to get to that place the exact settings to make).

So…any help you can give me would be greatly appreciated.

Here is a sample. Listen at the end after the VO.

That’s serious. I got the clip to pass ACX AudioBook standards, but it took a lot of work and I can still hear the putt-putting in the background. So no, don’t bother. That’s not going to work.

It’s there during your voice, too, but it’s harder to hear.

Rode NT1-A Cardioid Condenser Microphone with a USB connection.

The NT1-A doesn’t have a USB connection, so we need to know a lot more about how you got your voice into the computer. Some sort of microphone adapter? Does it have a maker or part name or number?


I forgot to mention that I have a PreSonus AudioBox USB 2X2 Audio Interface.

This microphone takes 48volt Phantom Power, so you have that button pushed, right?

Well, shucks.

This is one of the systems least likely to have noise problems like this. Usually, someone buys a cheapo USB adapter and it has trouble with the computer and starts making noises. That’s not how yours works.


OK, lets start with the obvious. Your recording is very low. You are intended to adjust your PreSonus volume controls so the Audacity panel looks roughly like this.

While you’re presenting, the bouncing light sound meter is supposed to get close to -6dB every so often like in the illustration. Also the tips of the blue waves should get about to half-way every so often.

See the little red “CLIP” light on the PreSonus? That’s your sign that you are presenting too loud. So there are little indicators sprinkled around as a guide for good announcing.

Being a practicing obsessive, I would stop Audacity and adjust the preSonus and announce louder and louder until the red light comes on just to see how much work I need to do to get it there. I’m betting you would have to turn the PreSonus all the way up, get close and bellow into the microphone to make that light come on, but it’s good to know those conditions. None of this will damage anything unless you scare the cat. The CLIP light is never supposed to come on during a performance.

Which three-number Audacity do you have? Is it possible to try a different USB connection? Do you have a lot of USB connections, like maybe external drives or a coffee warmer or something? More than a keyboard and mouse?


Nearby cell phone or other wireless device perhaps?

Put your cellphone in the garage for a bit and see if the problem clears up. If you were on a laptop, I would say do a recording from a different room … or the garage, just as a test.

If you plug headphones into the PreSonus, can you hear it? If you can, listen carefully and move cables around.

This is a stumper because you don’t have any of the usual suspects.


I don’t have a specific pulsing/ticking noise like that but in my basement, I turn off the gas furnace, any lights I do not need and just yesterday discovered that my LCD monitor makes a heck of a squeal. Even though it is outside of my booth, I can still hear it on the mic. Once I start Audacity and confirm my levels, I turn that sucker off. As mentioned, turn off everything you can. What lighting are you using to read? Read with a flashlight to test to make sure it’s not your light. Disable any and everything running on your PC that you do not need.

The Presonus is USB Bus-powered…

And no way to test with an external power supply. So the only thing to exclude the USB Bus-power problem, is by testing on another computer, preferably one that’s known to work well with USB Bus-powered audio.

But my money is on a problem with the phantom power. The NT1a is fairly power hungry. The Blue Snowball is not. It’s an electret, I think.

But my money is on a problem with the phantom power.

Some noise problems are unlikely (not impossible) to come from an interface that offers 48 volt phantom power. Just the act of making 48 volts means your unit has to have filtering and regulation of the USB battery. I would bet you couldn’t get “Yeti Curse” USB data noises through a system like that.

That’s not to say you can’t have other problems. Running Out Of Zot (technical term) is certainly possible. Once a system is starved of resources, it becomes unstable and unpredictable.