Developed and taught by Barney Brown, Office of External Communications
What is digital audio?
Digital audio requires turning everything we hear into 1s and 0s. When this happens, microphones and recorders “sample” sound waves thousands of times per second and at varying degrees of detail. The number of times per second (or frequency) and level of detail (or bit depth) gives us a quality setting we can record at.
By way of example, CD quality audio is recorded at 44.1kHz (samples per second) at 16 bit depth.
When recording audio for podcasts its best to aim for
- 24 bit depth
You can always reduce the quality at a later time, but if you record at a lower quality, you won’t be able to improve it later.
Signal to noise
When recording you need to decide what it is you want your listeners to hear (the signal) and what aspects of your recording you want to suppress, or try and hide (the noise). By way of an example, if you want to record a voiceover the signal is the speaker’s voice, the noise is everything else you can hear in the room where you’re recording.
You can emphasise the voice, and reduce the noise by:
- choosing a directional microphone
- adding dampening material around the area where you are recording to minimise reflections
- cutting low frequencies in the mix to reduce room hum
Recording the voice (or voices)
You need kit which can provide the following:
- a microphone
- a way of recording
At the least this could be a phone, at most this could be a microphone attached to a separate recorder. In this session we used:
- a SennheiserSennheiser directional microphone
- a zoom H4N
- a macbook (for editing)
- a piece of foam over the microphone to minimise “pop” (air shooting out of your mouth and hitting the microphone). Alternatively you could use a manufactured pop shield or some tights stretched over a coat hanger.
Make your own pop shield
Take a sip of water, position yourself about two fists away from the microphone, relax, and start to record.
Editing and cleaning up
Before uploading your audio you should:
- listen back to it
- edit it
- equalise it
- compress it
- add a fade in and fade out
You can do all of this with audio editing software like:
Editing audio in Audacity
Equaliser settings in Audacity
How to process vocals for podcasts or voiceover
The University has a service which (with permission from your supervisor) you can load audio into, ready for sharing online.
Streaming Media Service
Outside of the University you can use services like:
Audio hardware can be notoriously expensive, but for a good balance of quality, portability, and reliability, the Zoom H4N seems to be a good choice:
Because it has built in microphones you could record a podcast with just this bit of kit, using a computer to then edit the final results and upload it.
If you want to buy a dedicated microphone as well as a recording device (or you already have something to record onto) you need to think what kind of content you’ll be recording.
For microphones that are better for studio recording the sky is the limit re: price, you definitely get what you pay for. These are good all rounders though:
Very directional so good for recording a single voice. For something that records at a broader angle (for say recording multiple people at the same time, and picking up a bit of the ambience of the room) these are a good choice:
Investing a podcasting pack can be a good place to start as it often comes with a pop shield, and a stand (two things you should also invest in at some point)
For software there are lots of options ranging from free (Audacity), to free (if you buy new Apple hardware (Garageband), to paid for, and more flexible options like Adobe Audition or Logic.
Starting with Audacity is an excellent choice though as it’s free and will give you all of the tools you need to get started (cropping, fades, EQ, compression, exporting as various formats).