LF Rolloff for speech

Happy New Year,

Is the “LF Rolloff for speech” a setting recommended for all voice work or just audiobooks and what does it do?

all the best


It’s a rumble filter. Thunder, etc. Steve designed it as a mirror to the movie industry’s live recording filter. It doesn’t affect woman’s voices at all, but it can “tighten up” men’s voices a little. If you have a double-balls broadcasting voice, it’s not recommended at all, so it’s not universal.

Many people have trouble meeting AudioBook quality standards, and if you also have a cheap microphone, you can have bad sound that humans can’t even hear. This filter can swipe all those problems clear in one shot.

Also, not recommended for music.


It is audible on some voices, so if you start a project with it, you should finish with it.


Why not?
It’s one of the most essential things to do: high passing vocals (before compression).
If the filter doesn’t alter the voice too much, I would use it and even if it does, it may still sound better in the musical context as it doesn’t clash with low sounds.


I would call it the difference between Disaster Recovery and Graceful Vocal Processing. In its original form (I don’t think it’s called LF-Rolloff any more, but I don’t remember the settled-on name) it had the “length” Equalization optional slider all the way up. In this form, the tool is aggressive in slicing off low frequency damage, rumble, thumps and Stuff That Bothers The Cat. It could be the difference between making ACX presentation quality with minor damage and starting over with a new microphone or digitizer. There’s no question it’s running which is why once you use it, you’re stuck for the whole show.

Using the tool with the Length slider at 5000 (mid) instead of full up causes a slight “tightening” of the male voice and still retains most of its repair abilities and is recommended if you can get away with it.

Both of those options are stiffer than the movie version which has a more graceful thump and bump suppression and has beneficial effects without seeming to do so unless you’re really looking for it. The steepness of the drop toward the left is getting shallower and shallower as I go. I think there is a published High Pass Filter curve which works this way.

Then there is the entirely passive plug-on devices such as the Shure A15HP. That goes between the thumping microphone and the mixer or recorder. It’s XLR-only and it will pass phantom power. That one has a gentle suppression effect but almost invisible for sound damage.

I never tried it, but I guess if you slipped the Length adjustment all the way to the left for LF-Rolloff, it would more or less duplicate the more graceful (and sloppy) filters in this list.

As in any live capture work, the rescue can depend on how much trouble you’re in. Nobody wants to tell the Producer the shoot is trash.

I liked LF-Rolloff because it was a simple, defined filter that I could tune to get the results I wanted, and it was close enough to the movie version as to be interchangeable.

Any of these tools will be audible if you are Don LaFontaine and have vocal energy that appears on seismometers. That’s why I can’t globally recommend them. That effect is why you write Don Lafontaine checks (if he were still alive).

Almost all of these tools will emasculate Club/Dance/Disco and any organ pedal longer than 8 foot. No more Gloria in Excelsis.


I really wished I’d paid attention to how to apply this properly, because nearly all my narration sounds monotone and flat. I’m still going through the audio book I’m doing at the moment, and shocked to hear how much Roll Off has neutralised.

Low Rolloff is step one in the Audiobook Mastering 4 Suite.


The suite is designed so the tools clean up after each other and taking them out of order or leaving any out is not recommended. Depending on your recording/announcing/presenting style, you may want to add steps, but at either end, not in the middle.

Because mastering 4 doesn’t feature an Effect > Compressor step, it doesn’t have pumping noise and you can do other effects, filters and corrections either before or after your read. Two popular ones are Noise Reduction and DeEsser.

DeEsser doesn’t come with stock Audacity.


It’s strongly recommended you make WAV (Microsoft) 16-bit copies of each raw performance, so If Anything Happens during editing, you never have to read the work again. It is noted ACX puts great stock in having your chapters match, so you probably can’t tune each chapter (other than patching pops, clicks and wet mouth noises) and you can’t change your production technique in the middle.

On Wednesday last, BrittanyS was accepted for ACX publication.


all my narration sounds monotone and flat.

A pleasant, dynamic, interesting reading style is the reason you write checks to a professional announcer/actor. Audacity can’t change the ‘theater’ part of the work. If you’re trying to do Hamlet in a monotone, we can’t help you. You are also strongly advised against changing your reading style in the middle of the book.

This is Chris Pratt voicing Emmet in The Lego Movie. It’s an animation. They could have got anybody to do this. Chris is an actor.

All we’re doing is help you pass the basic technical standards for audiobook submission. All they’re doing is insisting on tight technical standards to prevent accidents and sound damage taking away from enjoyment of the work.


I’m … shocked to hear how much Roll Off has neutralised.

Did I miss the boat there? Are you complaining that Low Rolloff took the low, rumbly bass notes from your voice? If you have low, rumbly bass notes in your voice, then yes, it does that. You can try an alternative filter instead of Effect > Equalize. Try Effect > High Pass > 40Hz, 24dB > OK, and then the rest of the suite: RMS Normalize, Limiter, etc, etc.

You are warned that Low Rolloff is designed to suppress 60 Hz power hum in a recording. 60Hz is the power line frequency in the US. It’s also an audio tone and it easily leaks into recordings with home microphones. Low Rolloff also suppress sub-sonic home microphone noise problems. These noises can keep you from passing ACX Check and audiobook submission and it’s difficult to sort what happened.

If your voice pitch and power problems (in the US) overlap, then you could be embarking on a painful troubleshooting campaign. There’s no good way to separate the two sounds and you must fix your microphone system.

Submit a voice test to the forum. We’re particularly interested in the 2-second of silence at the beginning of the test. Don’t move or breathe during that time.


This may be the one and only time having a good broadcasting voice is a problem.

Do you have safety WAV copies of your original readings? If you do, then it’s a simple matter to apply the new filter. If you don’t, you may need to read it all again. We can’t take effects, filters, or corrections out of a recording. Once you close Audacity, all the UNDO goes away. Projects do not save UNDO.


No, that is not what it is designed for. The “Low rolloff for speech” setting is designed to reduce rumble and “wind blast” in voice recordings.

To filter out 60 Hz power hum, a Notch filter is the best tool for the job, though if power hum is a problem, there are usually many harmonics of the hum frequency that also need to be handled (but that is not the topic under discussion here).