TUTORIAL - Cleaning Audio - Professional tools and how to's

[psymedia]

I'm a professional in audio enhancement and editing with 20yrs experience both with music and forensic sound fields, I had a request to write a tutorial on how to clean audio like a pro with a few simple software tools.

I will start today with the tool kit required and over the coming days explain how to use them and produce a clean enhanced recording from that dirty hissy cell phone recording.

I will cover the following common issues, removing traffic or weather noise, removing (or at least reducing) music and tv noise, removing noise created from mains electrical interference "hum" such as air conditioning units, how to use a spectral analyser and graphic equaliser to reduce or isolate sounds, various methods to digitally increase the volume of an audio file based on the type of background noise, and anything else i think of along the way.

Part 1 - Professional Software

All methods i will describe are using 1 piece of software and 1 plugin with various utilities, to buy they are expensive, without condoning software piracy everything I mention here can be found by typing the name into google followed by the word to**ent.

Steinberg Wavelab - This is the interface for all of our work, wavelab is a professional editing and mastering package that is used to produce many of the songs you hear on the radio, tv audio tracks and dolby surround sound for theaters. Wavelab supports a plugin system used by recording studios for special effects, synthesizers, audio tools etc. we will be using the editing and analysis features of wavelab combined with a plugin tool kit called "izotope RX Tools"

So you just installed wavelab, you run the installer for Izotope RX, congratulations you now have a pro quality audio forensics lab.

When you open the program it will present you with 2 panes top and bottom of the screen you can drag a file into thew top pane, the top pane is your play window, the bottom is your file overview, both display the recording in the form of a wave where you can see increases and decreases in volume.

Open your first audio file in wavelab mp3s are decoded to wav format on first opening this can take some time - a 15hr 192kbps mp3 will take around 12 minutes to open and requires at least 2GB of free hard drive space on your PC for the temporary files. now we have our first recording in the editing window you will see if the file is over 10 minutes long the time gradients of the window are in 10 minute increments which makes it very hard to visually spot anything, in the bottom right of the top pane you will see a horizontal slider, moving this will increase or decrease the length of time displayed in the top pane, click this until you see the markers change from 10 minute resolution to 1 minute, this gives you a display where 1 minute takes up about an inch of horizontal screen space so you can see the audio events well enough but still have about 15 minutes across the entire screen the full resolution extends from microseconds displayed per inch thru to many hours per inch. to the right of the horizontal time slider we have the "amplitude" resolution ie the volume resolution, if your recording is very quiet as you increase the resolution you will see the waveform start to show you the hidden quiet sounds.

Part 2 - Basic increases of volume where there is little background noise:

Theory First - If the loudest noise in your recording is minus 15Db and we add 5Db gain we get a maximum level of minus 10Db, in any audio editing be it music, tv, film or love songs for adults our goal is to get the loudest noise on the recording as close to 0Db as possible, above 0 will start to distort sounds, most of the tools we will use have settings in the scale of decibels so it's a term and theory you need to understand.

if your recording is just a little quiet the quickest thing you can do is to use one of wavelabs built in tools. Click on the menu with the heading "process" then select "change level" here you will be asked to supply a number in decibels which will be the amount of gain will be applied, enter 5db i find this is a sensible amount to start with, click apply, and you will see the waveform displayed just got a whole lot chunkier on the vertical axis, review the audio if it is still quiet you should still see the gain increase window and you can click apply as many times as you like until things become audible. You will notice that the more you increase the gain the more hiss starts to appear if a cheap / low quality recorder / phone was used don't worry about this i will cover it's removal in a later installment of this tutorial, i regularly clean up recordings from 10yr old telephones to a reasonably good quality output file.

Enough for today if your following get your software installed, familiarise yourself with the wavelab interface and boost the volume of your first recording. more in the following days.....

[Onlooker]

I really appreciate this Psy!
I expect most people on this forum rely on Audacity to improve their files. I guess might see where it falls short compared to Wavelab.

Thanks a lot for this!

[reggind]

The copy of Izotope that I demoed from that source was rife with viruses. I would not say don't play with it, but I would strongly recommend that you play with it on a VM at least at first. It does seem to be cool software. The echo removal tool was pretty neat if used very judiciously. I did not find the rest of the tools to be significantly better than Audacity, and that has the big plus of being free. The interface on the Izotope suite was a lot nicer, but you don't hear the interface.

The problem is at the end of the day, most of the tools we are working with are for cleaning up the dominant sound in a file, while with this hobby, we are after the stuff that these things want to sweep under the proverbial carpet. We are after the little nuances that are almost totally buried in the noise, obscured by echos or drowned out by the TV/Radio/HVAC etc.

[Shadyone]

im trying to use my phone to record. its the only thing i have to do so. an android. using a random app i found on google play. is there anyway to get the sound onto my laptop in order to clean up sound?

[reggind]

The first thing you need to do, and perhaps the hardest thing is to find the file. Pay attention when you save it, assuming it gives you any options. If the file seems to be lost, there is a program that I use called ES File Explorer. You can poke into all the directories on the phone (Manually, and yes, it is a pain in the ass) and find the file. Once you have found the file you have a few options for getting it onto your notebook.

If the file is under about 15MB, you can probably attach it in an email and send it to yourself. This is not the fastest way but it is probably the simplest.

Next up, assuming your notebook has a SD card slot on it, is to use ES File Explorer to move or copy the file from wherever it is to someplace on the SD card. Than you can plug the SD card into your notebook and access the file there.

Last up, if you are at all computer savvy, you can set up a LAN connection in ES File Explorer and access a shared folder on your notebook directly from your phone. This is the easiest once you have it set up.

There are no doubt some other ways to get from hither to yon. You could use an app like dropbox and get the app for both your phone and your notebook..

So, there are a lot of ways to skin the same cat so to speak. I have given you a few to think about.

[yeppie]

im trying to use my phone to record. its the only thing i have to do so. an android. using a random app i found on google play. is there anyway to get the sound onto my laptop in order to clean up sound?

The android phones I know (HTC, Huawei, Samsung) come with their own software tool to connect the phone to a computer. All you´d need would be an USB cable.

[Shadyone]

I have a lg4. I used a app called smart recorder. Ot gives me the option to share.. But when i send it to myself via outlook\gmail\text etc. It never actually sends.
I will try sending to soundcloud then DL it on my laptop

[jinhui]

Usually (android) smartphones can be set to "mass storage mode" when connected via USB cable. This will allow you to access the internal (built-in) and external (sd card) memory via your (windows) file explorer. If the smartphones memory is encrypted, you might also need to unlock your phone first by entering your passcode. As an recording app for android I can recommend "AudioRec" (also called Aufnahmegerät) from AC SmartStudio.
Tipp: Set the recording to +20db within the app settings.
But in my opinion recording with a smartphone is just a compromise when you don't have a decent recorder with you but still want to try to capture "something".

Best regards,
jinhui

[GarfensX]

wow, somw pro-tips right there. Thank you.
I usually just go with Audition and use the built in NR.
I haven't been recording for too long and most of the time it's just way too quiet to hear anything.

Been practicing with the recordings I got from my gf and me for the rare occasion when I do finally get a good recording... Been using Adobe Software for 10 years and figured that Audition is top-tier but I guess you are the pro with 20 years of experience xD

[reggind]

Audition is a great piece of software. There are a lot of great pieces of commercial software for audio. The thing is at this point in my life I don't have money for software and I don't believe in using pirated software, so I just default to Audacity, which is free. I don't mean to imply that the commercial stuff is not as nice, I just can not afford to play with it. However if you are advanced enough to be willing to shell out the kind of coin you have to for commercial software you probably know what you are doing with it.