Removing buzz from my audiobook

Hi all,

I’m hoping someone can help me to resolve something with my audio recording. I recorded a short story about an hour in length. I was careful with the recording but, no excuses here, obviously not careful enough because about half way through I realised I had my mic too close to my desktop. The result was the buzzing sound which I see is all too common. Using noise removal I managed to clear it except for the actual spoken parts. So the silence is nice and clear, but the buzz still occurs whenever I speak.

Once I discovered the problem about half way through the recording, you can hear it goes away (because I moved the mic away from the desktop) but there’s a slight hiss behind my vocals at that point onwards.

One step at a time though: is there any way to remove the buzzing from the spoken parts? I’ve attached a 25 second sample below to show what I mean.


Sample with buzz.aup (2.6 KB)

The file you posted is an Audacity .aup file, which does not contain the audio clip, it only hold pointers to where the actual audio lives (presumably still on your computer). Use the “File”->“Export” or “Export selection” to create a .wav file of you sample clip and post that.

Ah sorry flynwill - ok I’ve done that now. Thanks for your patience. It’s only a short clip because I tried a longer one and it was too large.

Can you post that same clip as a raw capture? Before you processed or did anything to it?

Ah, problem. Unfortunately I don’t have it as a raw capture. I didn’t save it before I made any changes so don’t think I can get back to the raw version (unless you can tell me otherwise!)

Ah. Always keep a copy of your original recording – in photographic terms that’s your “original negative”, either export as a .wav (bit depth and sample rate matching your capture settings) or make a backup of the audacity project directory. Exporting as .wav will take less disk space.

My guess is that it’s going to difficult to do much better than what you already have managed with the noise tool. You could try just doing another application of the noise removal, but don’t repeat the “get noise profile” step, as with a bit of luck the noise profile from the first application should still be there.

If you can recreate the noise by putting the mic back back on the desktop post a clip so we can hear what it really is we might be able to advise further.

I was able to take the edge off it a bit with some equalization basically a notch filter from about 3-5 kHz, but you may not like the effect on your voice. You can reduce the buzz more by bringing the low side of the notch lower but it starts effecting your voice pretty strongly.


I don’t have it as a raw capture.

So that’s the first thing you have to fix.

Make up a raw capture sound clip for posting on the forum.

I don’t have the pictures, or the links or the web page yet, so none of that is going to work. Later.


Make a ten second mono sound test file.

Set up your normal recording studio and open Audacity 2.1.0 set for 44100, 16-bit mono, not stereo. If your recording or microphone system is locked into stereo, that’s OK. You can create mono later.

Start Audacity recording. Hold your breath and stop moving for two seconds. Breathe and start talking/announcing/presenting in your normal volume for about eight more seconds. Anything. Read the milk carton. Stop. You can go under time, but shouldn’t go over. Click- drag and delete anything over ten seconds total. This a technical test, not theater.

If you have two sets of blue waves one above the other, you’re probably in stereo. Use the little black arrow drop-down menu to the left of the waves > Split Stereo to Mono. [X] Delete one set of waves.


If your clip is significantly different from this picture (waves too high or too low), then that’s the first problem. The goal is tops of the blue waves at about -6dB on the red sound meters. Yes, you do need to watch the sound meters and the script at the same time.

File > Export Audio > WAV (Microsoft) sound file for your analysis [link] or posting on the Audacity forum. Scroll down from the forum new message panel > Upload Attachment.

Thanks flynwill, I’ll have a look at what you said and also post a new file of the buzzing effect before I’ve tried to clean it up.

Koz, is that basically what you’re saying? Do the paragraphs in bold apply to me?


flynwill, this is a sample I’ve just recorded with the pure unadulterated buzzing!

Ah! Your buzz looks a lot like the LP surface clicks…

I ran your samples through “click repair” and got the attached.

Click repair is not free software, but it may be worth the $40 to you to save this recording. (If you ever decided to digitize your LP collection it’s a very useful tool).

Wow that is pretty good software huh? Yes I might consider that in future.

Ah, but you do get a 14-day free trial …


I can’t help wondering if this is a grounding problem in the recording system, particularly since the tones making up the buzz are all multiples of 60 Hz, the power frequency in the US: 60, 120, 240, 300, etc.

We took you at your word that you’re required to clean up this recording, but if you want to prevent any future ones, we have some work to do.

How are you recording your voice? I mean pretend I want to go out and buy what you have and connect it the same way.


I’m using a Samson go-mic. I plug it into the USB port of my desktop, then plug the headphones into the mic.

I’m sure you’re right about the cycles and what have you but I’m in the UK, so not sure if that makes a difference. Also, when I bring the mic away from the desktop, the buzzing stops. It’s what I (who don’t have any technical knowledge whatsoever) would put down to ‘interference’, correctly or not.

Fascinating you have 60Hz interference in a 50Hz country. So you already know how to correct the problem at the recording stage. USB microphones are not a gift from the angels. They can have very serious noise problems from bad connections, poor quality USB services and as you’re finding, interference from poor shielding. Flynwill is testing third-party devices that claim to be able to help “clean up” some USB microphone noises. Good quality microphones are all metal because of shielding required.

Microphone signals, the signals from your voice before boosting, are super tiny. I call them the butterfly wings of the electrical world. Unless shielded from interference, anything powerful that’s generating radiation can cause buzzing and other noises. Plastic microphones may not be up to it. As a test, operate a portable AM radio next to your computer.

You can use patching, filtering, and noise reduction in Audacity post production to “rescue” the performances, but that almost always causes other sound problems. Best to not create the noise in the first place.


Actually if you look close at “Raw sample.wav” the noise is ~230 uS pulses repeating every 10 mS (100 Hz). Exactly what you would expect from something like a florescent lamp, or power supply rectifier running of 50 Hz mains. From Paul’s description it sounds like the interference is radiated and not due to any sort of ground loop or grounding issue. In any case the solution is clear, keep the mic away from the noise source and it is fine.

That buzz is 100Hz fundamental + harmonics .

There is a software solution using the [notch] code below in Audacity’s Nyquist Prompt

(setq mysound s)
    (setq q 5)         ; set the base Q for the filter
    (setq iter 150)     ; set the number of iterations
    (setq freq 100)  ; set base frequency

    ; start the DO loop
    (dotimes (i iter mysound)   
    (setf mysound (notch2 mysound (* freq (1+ i)) (* q (1+ i))))
    )                     ;end of loop

But eliminating the source of your 100Hz interference is the real solution.

Thanks Trebor, I’ll try tthat. I haven’t added Nyquist yet (I’m new with Audacity) but I see everyone talking about it so I’ll have a look at that and give your solution a go. Thank you.

Ah I see I already have Nyquist Prompt with my current Audacity!

You have to post the code in my previous post into the Nyquist Prompt window …
100Hz interval Notch-code in Nyquist Prompt.png
Then apply Nyquist Prompt, just like any other effect , to your buzzy audio,

This post-production software-solution to the buzz isn’t as good as preventing the buzz in the first place:
the notch-filter processing adds artefacts : post-processing it sounds like you’re talking down a tube.

It’s possible your buzz is caused by other software interrupting audio-capture every 1/100th of a second.
You could try switching off unnecessary things like internet connection whilst recording.
Competing sound-capture programs (Skype?) are another possible explanation for the pulses every 1/100th of a second, when they fight over the audio-input.