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Free NewsletterWelcome to part 3 of my series on podcasting. This week I’m going to talk about podcast editing – how to make your podcast sound its very best and give it that professional radio studio sound. If you have listened to many podcasts you probably have noticed that some have really horrible sound quality – especially when guests are involved. You can have a great sounding podcast, but it requires a bit of editing.
In the previous two parts, we covered an introduction to podcast formats and also podcasting equipment. While good equipment helps, having great content and the ability to edit for good sound quality is probably more important. I could take a mediocre microphone and make it sound pretty good using the right editing techniques, but no one is going to listen to a dull boring podcast, even if it sounds great.
So this week we’re going to start with basic editing techniques and tools, and then go into more advanced tools and techniques as we get farther into the article. Not surprisingly the software cost and time needed for editing goes up as you get to more advanced techniques.
Quick and Dirty High Quality Podcasting
Lets assume you are starting with a very simple podcast setup – perhaps a USB microphone and the use of skype (covered in part 2) for hosting guests. You record directly to your computer from the microphone or using one of the skype recording programs covered in part 2. I’ll also assume that you have at least taken some basic steps to get a quality recording by making sure your microphone input levels are correct and you have minimized background noise, and stored it in WAV format which is an uncompressed audio file.
What’s the quickest way to make your recording sound good? A little free tool called The Levelator is where I would start. It’s available for PC, Mac and Linux. What does it do? Its a combined leveler, compressor and limiter – and it’s easy to use. Just drop your WAV file onto the levelator and it will level, compress and limit it all at once to make it sound better.
For a quick and dirty solution, I have found none better – and your audio will sound better than all of the low quality podcasts on iTunes if you use it. The only disadvantage is that it is not really a sound editor, so you can’t cut out bad sections – which we’ll show you how to do next.
Audacity
Audacity is a full featured (and free!) sound editing program available for PC, Mac and Linux here. It lets you actually edit your audio file so you can take out your nasty mistakes, long silent pauses and 20 second ummms and ahhhs. It is not hard to use the basic features – you just open your audio file and start editing – cut/copy and paste work as you might expect and there are a set of pretty advanced audio tools you can play with as you get more experienced. Also a number of video tutorials and written tutorials are available on the internet to help you use it effectively.
Audacity and the Levelator make a nice combination. The quick and dirty way to use Audacity is to open your audio file, cut/copy and paste your audio to remove your mistakes and then save the edited file as a WAV file. Next take your edited WAV file and run it through the Levelator to make it sound good. Finally, bring it back into Audacity so you can write the finished mp3 file out.
Podcasts are published as MP3 files, so you do need a plugin (called LAME) for Audacity (details on how to install it here) to write mp3 files from within Audacity, but installing the plugin takes only a few minutes.
Advanced Audio Editing Effects
While the Levelator is a nice all-in-one tool, it does not provide the perfect solution in every situation and has limited options for configuring. If you were to look under the hood of the Levelator, or even take a look at the equipment used in a radio studio you would find that there are a few key effects being applied to edited audio signals to make them sound great. So here they are:
The Gate
An audio gate is an effect that cuts out sound below a certain level. This is how radio stations, for example, get true silence once the host stops talking – even if he’s shuffling papers around on the desk. A gate cuts out all background noise that does not rise above a certain volume level. A gate can be implemented in either hardware or software – many radio stations have hardware gates tied to their microphones to cut background noise in real time. I use a software gate to cut noise out in my podcasts. Unfortunately Audacity does not have a pure gate function, but the noise removal tool can be used to cut some background noise.
Gates generally have three main settings. The most important is the level of the gate - which is simply the volume level where it cuts in. As long as the background noise is below the volume level, the gate will cut out the background noise. The other two settings have to do with how fast the gate cuts in and out (called attack and release) – and these are adjusted so the beginning and ends of words are not cut off when you start or finish talking.
The Compressor
The compressor is the magic effect that gives your voice that deep, radio voice sound. Like the gate, you can purchase hardware compressors for real-time audio or you can use software to compress the signal when you are done. Audacity does come with a gate effect.
What it really does is level things out – you see as you talk naturally your voice volume tends to go up and down quite a bit. While this is fine for face to face conversation, it can be distracting on the radio. So what a compressor actually does is lowers (compresses) the volume of the your voice (when above a certain level) when you are at a peak so everything is roughly the same level. Then it boosts the volume level of the entire conversation so it sounds like you are talking at the same level all the time.
The net effect of the compression and boosting is that your finished audio has a more consistent (though limited) dynamic range – making your voice appear louder and more forceful. If you compress your signal a lot you will get something much closer to a radio DJ sound – also many pop music songs are highly compressed.
The three main settings for a compressor are the threshold and the compression ratio and gain. The threshold determines when the compressor will kick in – all sounds above the threshold volume level will be compressed. The compression ratio determines how much to compress the signal – 5:1 is typical for many voice applications. Finally the gain determines how much to amplify the finished (compressed) signal back up to get back to “normal” levels after compression.
One adverse effect of compression is that it raises the level of the more quiet parts of the audio – including the background noise. That’s why you don’t want to “overcompress” your audio as it will increase the noise you hear in the background while talking.
The Limiter
A limiter can be thought of as a reverse gate – it either cuts off or lowers the volume on all signals above a certain level. This can be helpful if the host or guest starts shouting, or if you want to boost but limit the volume level of your entire show up to a fixed level so you get consistent volume from show to show. Again it can be done in hardware or software. Audacity does come with a hard limiter.
A limiter is often used in conjunction with a compressor – you typically compress the signal (with amplification to bring it back up) and use a limiter to soften the loud peaks and provide a nice finished product. In fact the compressor/limiter/gate is a pretty inexpensive piece of hardware you can add to your studio if you plan to do real-time broadcasts.
The Equalizer
Most people who own a large home stereo are familiar with the equalizer. It lets you boost or lower the volume of different frequencies. In its simplest form – such as your car radio – you can boost your bass or treble tones by turning one knob. If you move to a fancy home stereo or mixer you often have several knobs you can use to boost bass, mid-range and high frequency audio.
If you have moved up to a mixer for recording your mixer likely has a built-in equalizer where you can adjust the low, mid and high frequency band volumes. You can also apply an equalizer in software (Audacity has this).
In practice, I will often use the equalizer to boost the bass in many guests, filter out mid-frequency “ssss” sounds, and on rare occasions even filter out some background noise such as a computer fan humming at one frequency. However, for the most part, I tend to set up the mixer so each microphone sounds good and then leave it alone.
A Noise Filter
I rarely use a noise filter anymore as proper gating will cut out most of the background noise in the studio. However, in some situations – such as live recording in a noisy room or a remote live location – a noise filter can come in very handy.
Most noise filters are implemented in software (Audacity has a Noise Removal tool). What you do is select a section of audio where no one is talking that the software can use to build a background noise profile. The software then uses that background noise profile to remove as much of the background noise as possible.
The downside is that along with the noise some of your actual audio signal is also cut out – so using a noise filter will change the sound of your voice and that of your guests. In very noisy environments the results can be pretty dramatic and noticeable, so it is always a compromise to decide how much noise to let through in the finished recording.
Advanced Editing in Audacity
Now that we’ve covered the basic effects available, lets look at how you might apply these to a finished show using a free tool such as audacity. Here’s how I might edit a show:
- Cut and Paste Editing – Before I apply any effects, I will usually make a pass through the show and cut out any major mistakes, awkward pauses, swear words, etc… I’ll also paste in my intro music, transition music and any other announcements I might want to make at the beginning or end of the show so it is basically in a finished form.
- Gating/Noise Removal – Since Audacity does not have a pure gate, I would probably use the noise removal effect here to cut out as much background noise as possible. If you are using another audio tool, you would apply the gate here to completely remove background noise during the silent parts.
- Compression - Use the compressor effect to compress the audio. For talk podcasts I recommend starting with a 5:1 compression ratio. Check the “Normalize to 0 db after compressing” box – which will raise the level of the audio back to a consistent level after compression. You may need to tweak the threshold a bit depending on how loud your source signal is.
- Equalization – I normally use the equalizer on my mixer to adjust incoming sources, but if you want to equalize a bit here you can.
- Hard Limiter – While not needed for all shows, if you still have some excessively loud sections you can limit them here with the hard limiter effect to provide a more consistent volume level throughout.
- Export MP3 file- Use the “Export as MP3″ command on the file menu to export your finished podcast – podcasts are generally published on the internet as MP3 files
Beyond Audacity – Podcasting with Reaper and Adobe Audition
If walking through all six steps above sounds time consuming and tedious, it is! The problem with a program like Audacity is that even after you have manually edited the bad parts out of your podcast, you then have to apply all of the effects one at a time to your podcast.
The program I use for editing is called Reaper. While not used by many podcasters, I picked it primarily because it had a significant price advantage over the gold standard for sound editing which is Adobe Audition. Adobe Audition runs several hundred dollars for a single license, while Reaper runs well under $50 for most home podcasters (though their large business license is a bit higher).
Reaper and Audition both have features that let you set up a series of effects like the ones just described (called an audio chain) and apply them to your audio track consistently – usually in a single step. This avoids having to apply each effect one at a time (like we did with Audacity) and ultimately saves time. Also I can ensure that I’m applying the same effects to my podcast from week to week giving it a consistent sound.
Finally, if you eventually move up to multiple track recording (guests on separate tracks for instance), both of these programs fully support multi-track editing which lets you apply effects separately to each track and remix the tracks to get great sounding audio even if one of your guests had an equipment problem or a lot of background noise.
Summary
There are a lot of lousy podcasts out there – don’t be one of them! Audio editing is a certainly an art – which is why top professional sound engineers spend years perfecting their trade. However, even a little bit of editing can go a long way towards improving the sound of your podcast and giving it a professional finish.
For beginners, an all-in-one solution like the Levelator will give you a jump in quality over an unedited podcast. If you need to do some simple editing or effects, consider using Audacity for cut and paste followed by the Levelator for finishing. The next step above that is to apply your own sound effects (compression, noise filtering) using something like Audacity. Any of these work great for a first time podcaster and are free.
Later after you have some experience under your belt you might want to upgrade to a more sophisticated program like Reaper or Adobe audition – if only for the time it will save you.
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