What’s the best way to record audio and achieve professional sounding results? It’s not as expensive or as difficult as you might think. For the average Podcaster or for dialogues and presentations, it’s relatively easy to get set up and start producing high quality audio material like a radio station. Let me explain some of the basic principles…
What you start with determines what you’ll end up with
The quality of your unprocessed, uncompressed audio recordings will determine the quality of the end results. Getting the best possible recordings in the first place should be your top priority. This comes down to two things: the equipment and the techniques you use to record it.
Choosing the right microphone
A cardioid pattern mic records sounds in front of it
The starting point is a good quality microphone but also the right type for the job you have in mind. Luckily, with the growth of Podcasting and computer based audio recording in general, there is a wide selection of microphones available and they’ve come down in price quite dramatically in the last few years. Choosing the right kind of microphone is just as important as the quality. There are basically two types: unidirectional, also known as cardioid or hyper-cardioid microphones, and omnidirectional, also known as border microphones. What’s the difference? Unidirectional mics only record sounds that are directly in front of them, whereas omnidirectional mics record sounds coming from all directions.
Which type should I use?
A shotgun mic cuts out unwanted background noise
In most cases, it’s best to use unidirectional mics. This is for general studio recording and out on location for things like interviews or news reports. Use an omnidirectional microphone to make mono recordings of two or more people in a quiet room. Omnidirectional mics are sometimes used as “border mics” that pic up additional background noise or ambient noise and recorded as a separate track that is mixed in later. In situations where you expect a lot of background noise such as in town centres, shopping centres, schools, universities or cafes, it’s advisable to use a “shotgun” mic. These are extremely directional and do a pretty good job off cutting out any sound that isn’t directly in front of them. Professional quality camcorders often come equipped with a shotgun mic.
Get the right connections
An important thing to bear in mind is how you intend to connect it to your recording device. If it’s a DAT, Mini-disc or your computer, check that the mic can be easily plugged in. Some mics require phantom power (48v) which can only be provided through a good quality mixing desk, although many good quality condenser mics include a battery compartment so that phantom power is not necessary and you can plug them directly into your recording device. Cheaper consumer condenser mics often require what is known as “plug in power” or have a battery compartment built in. Most modern digital recorders, such as MiniDiscs and dictaphones, include plug in power so the battery compartment is unnecessary. Computer plug in power is different to digital recorders and you may experience compatibility problems with some microphones. If in doubt, test microphones before purchasing or you can always buy good quality purpose made USB microphones that are typically sold as Podcasting mics.
How can I make a stereo recording?
A coincident pair of mics to make stereo recordings
The easiest way to make a stereo recording is to use what’s known as a coincident pair. It’s basically two microphones crossed together pointed at either side of the source(s) of the sound. There are specially designed “stereo mics” that have two mics inside a single unit. While they’re quicker to set up and more convenient, you’ll definitely get better results with seperate mics, plus you’ll also have the option to use them for interview style studio or location recording.
Beware of the term binaural recording. This is not stereo recording as we all understand it, is intended exclusively for use with headphones and attempts to reproduce a “live” listening experience. There’s a sample binaural recording on the Wikipedia.org page on the link above. Try listening to it with headphones and through your speakers to hear the difference.
Microphone technique and placing
Having good quality microphones is only half the story however. It’s quite possible to make terrible recordings with top quality mics. The position of the mic(s) relative to the speaker(s) and other sources of sound will also determine the quality of your recordings. Here’s some basic advice:
Correct distancing
If you’re talking into a mic, you want it to be about 20cm away (or the distance between the tip of your thumb to the tip of your little finger when they’re outstretched) from your mouth and not directly in front of it. Having the mic directly in front of your mouth results in “popping” where consonant sounds such as “p”s and “b”s send a wave of air directly into the mic and distort the recording. Most people hold the mic slightly lower than their mouth but positioning it to the side usually gives better results. By the way, most headset mics are positioned way too close to your mouth and usually use poor quality mic capsules with low sound sensitivity to compensate.
Avoiding handling noise
If you’re making stereo recordings or using a fixed position mic (i.e. not hand-held), use a mic stand on the floor whenever possible. Putting stands on a table increases “handling noise”. This is when the mic pics up vibrations through the mic stand or from your hands when you’re holding it, touching the table, etc. Be conscious of this because it can ruin a perfectly good recording!
Beware of background noise
Also be aware of all other sources of sound in the area where you’re recording. Human ears naturally filter out background noise but mics are not so smart. For example, you might not notice the sound of the fan on your computer but you’ll certainly notice it when you listen back to the recording.
Recording directly onto PCs and laptops
Most computers come equipped with fairly good quality sound cards so you can just plug in a mic and press record on your favourite recording software. If you’re lucky, you won’t have a problem with hum and hiss when recording with microphones directly onto a PC or laptop. Unfortunately, this seems to be a very common problem and it usually has nothing to do with your microphones, mixers, gain levels, etc. as you might read on some on-line forums. The most common cause of hum and hiss is from the sound card in your PC or laptop picking up noise from the hard disc drive, CPU, cooling fan, etc. inside. You can check if this is the problem by unplugging your microphone and recording a few seconds of no input. If you still hear hum and hiss on the recording, then it’s most probably the sound card. Fortunately, you can buy external sound cards that will remedy the situation. Professional quality ones start at around £100 (16 bit, 96 KHz) and budget ones at around £30 (16 bit, 48 KHz).
Monitoring
Listening to what you’re recording in real time is a big advantage, especially in improvised or experimental situations. It’s also incredibly useful for learning about how best to position mics. In a recording studio, you have the luxury of a sound proofed mixing room but in real life and out on the road, this isn’t always possible. Headphones that isolate your ears from the outside world are an excellent option, in fact, I’ve found that a simple, relatively inexpensive pair of Sony ear-plug style ear-buds allow me to monitor mic recordings in almost any situtation.
Choosing the correct recording formats
I always record in an uncompressed format because digital compression such as MP3 and AAC is “lossy”. Lossy means that you lose a lot of detail and resolution in the sound and as you edit and process it, the quality of the sound diminishes. Just as it’s important to edit and process digital photos with the highest pixel resolution possible, it’s equally important to edit and process audio recordings with the highest bitrate and sample frequency possible. If you can, record directly to 16 bit WAV (Windows) or AIFF (Mac) files with a sample frequency of 96 KHz (96,000 Hz). However, this professional quality recording isn’t always possible so 8 bit WAV/AIFF files with a sample rate of 44.1 KHz (44,100 Hz) are perfectly adequate. Good audio recording software will have these options available. When you have edited and processed your recordings and you’re happy with the results, then it’s time to convert them to MP3 or AAC for distribution over the Internet.
Which output format should I choose MP3 or AAC?
It depends on what you want. MP3 is the most widely accepted and compatible format. While Flash Player, the de facto multimedia platform on the web, supports both, some MP3 players do not support AAC so bear this in mind when choosing a format. The main advantage of AAC over MP3 is that it preserves better audio quality at very high compression rates (smaller file sizes) and the main advantage of MP3 over AAC is that it is much better audio quality at low compression rates (larger file sizes). Both formats support DRM (digital rights management) but both can be easily defeated with readily available 3rd party software.
Which software package should I use?
In my opinion, the easiest software package for non-professionals to use that produces the best results is Adobe Soundbooth. It isn’t cheap and if you’re on a budget, I’d recommed using Audacity which is free. There’s a list of digital audio editors here. Whichever software package you decide to use, make sure you can do the following easily:
- Set the overall volume (gain) of the audio tracks.
- Fade tracks in and out.
- Cut, splice, paste, move and delete sections of a track.
- Add audio effects and processing such as compression, reverb, EQ, noise reduction, de-esser and aural exciter (Ideally have a selection of optimised presets for things like “radio leveller” or “female voice”).
- Set the sample frequency* when recording and converting to MP3 (e.g. 44.1 KHz).
- Set the digital compression bitrate when converting to MP3 (e.g. 56 Kbps).
* Flash Player only supports sample frequencies of 11, 22 and 44.1 KHz and compression bitrates under 128Kbps. It does not support variable bitrates.
A final word
There’s a lot to learn about making good, high quality audio recordings but understanding a few basic concepts will help enormously. Of course, the best thing to do is get set up and experiment, try different things out, push things to the extreme and see what results you get. Above all, do lots of it and have fun while you learn. Good luck and happy recording! 
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In February 2009, I released the first beta version of the FLV Player plugin activity module for Moodle. It leverages the ubiquitous JW FLV Player and has been very popular among teachers and course content developers working with Moodle. I’m working on a substantial update for the module and in this article I’m going to write about some of the improvements and new features in it.
