Recording Audio back BACK

 

Photo of Dan LaValley
Dan LaValley
Manager
Biology New Media Center

Thanks to Dan LaValley of Learning Technology & Distance Education for creating this tutorial.

  1. Selecting a Good Location
  2. Using the Appropriate Microphone
  3. Different Media Formats and Choices
  4. Monitoring the Recording


The basic properties of a good recording depend on what kind of recording you are doing. For the most part, you want a recording with a fair dynamic range - low background noise and clear, audible audio of the subject of your recording - be it a speaker or frog calls. The basics to remember are: selecting a good location, using the appropriate equipment and microphone, and getting good levels.

 

Selecting a good location

As they say in business: location, location, and . . . location. If it is possible to control where you do your recording, try to find a location that has low noise levels and has a lockable door so people can't walk in on you. Computers and air conditioning with the low level hum of electricity and fans are your enemy when trying to get a good recording. Access to a sound recording studio is, of course, the best case scenario! However, many of us don't have access to high end recording studios and can't completely control the location. To some extent, this can be alleviated by using an appropriate microphone or in post when you are editing.

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Using the appropriate microphone

When you buy a stereo, they say the most important component is the speakers because it's the speakers that are actually physically reproducing the sound. For recording audio, the most important component is the microphone because it determines what the audio sounds like when it is recorded.

For specific information on selecting microphones for desktop narrations, click here.

 

Omni directional microphone pickup pattern

Omni
The simplest microphone design will pick up all sound, regardless of its point of origin, and is, thus, known as an omni directional microphone. They are very easy to use and generally have good to outstanding frequency response.

 

Cardiod microphone pickup pattern

Cardioid
This pattern is popular for sound reinforcement or recording lectures where class noise is a possible problem. The concept is great - a microphone that picks up sounds it is pointed at. The reality is different. The first problem is that sounds from the back are not completely rejected, but merely reduced in volume. This can surprise novice users. Another issue is that the microphone will emphasize the low frequency components of any source that is very close to the diaphragm. This is known as the "proximity effect", and many singers and radio announcers rely on it to add depth or "chest" to a basically light voice.

 

Shotgun or supercardiod microphone pickup pattern

Shotgun
It is possible to exaggerate the directionality of cardioid type microphones, if you don't mind exaggerating some of the problems. The shotgun is extremely sensitive along the main axis, but possesses pronounced extra lobes which vary drastically with frequency. In fact, the frequency response of this microphone is so bad it is usually electronically restricted to the voice range, where it is used to record dialogue for film and video.

 

Lavaliere
The lavaliere (or lav) microphone is commonly used with wireless systems so a speaker can move around freely without being tied to a microphone stand or podium. The pickup range is small and the mic is usually clipped to a shirt or lapel.

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Different media formats and choices

Some of the common choices available to faculty and staff will be tape decks, mini disc recorders, video cameras (You can still record audio to a video tape even if you don't want to use the video!) and recording directly to a computer.

Marantz tape deck with attached microphone

Audio Tape
There are both low and high end tape decks available on campus. Everyone knows how to use a tape deck - push record. In addition, the higher end Maratnz decks allow you to monitor the recording both with a set of headphones and level meters. The disadvantage is that audio tape is not especially sturdy, degrades over time as it is played, and has background tape hiss.

 

MP3 Player and Recorder

MP3 Player / Recorder
With digital formats becoming more popular, certain mp3 players have the ability to record audio directly into a digital audio format. These devices are small, reliable, and can store massive amounts of audio without the need to switch tapes. Certain models can store upwards of 5 hours of audio to a wav or mp3 format. This would be idea if you'll need the audio to be used on a computer because you wouldn't need to capture it on the computer in real time, thus saving you time. Even with certain advantages, high end mp3 recorders are expensive and the internal hard drives may stop working after extreme shock.

 

Mini disc player / recorder

Mini Disc
Mini disc recorders and discs are both compact, easily portable, sturdy and high quality. Using the mini disc recorder for lectures or interviews with an appropriate microphone attachment works well. One disadvantage is that recordable mini discs are somewhat harder to find than audio tapes. The second disadvantage is that the audio recorded to a mini disc is compressed in order to fit on the smaller media. For some audio recording purposes in which the audio has to be analyzed scientifically for certain frequencies, the mini disc recorder is not appropriate because the compression artificially degrades the audio signal. While many people cannot hear the difference, the audio compression would definitely color any scientific analysis of the sound.


Video camera with attached microphone and headphones

Videotape
An often overlooked source and somewhat more common resource for doing audio recording are video cameras. While not built specifically for audio recording, they nonetheless can record good audio given an appropriate microphone attachment. The disadvantage is that you cannot monitor the recording with some consumer video cameras to tell if the signal is too soft or too loud. The only way to combat this is to do a short test recording and then rewind and play it back with headphones connected to the camera to tell if you are getting decent audio levels.

 

Recording to a Computer
The advantage of recording directly to a computer of course is that there is no intermediary media to deal with and you save time. This would most commonly be a choice if you have a laptop or a controlled location like a sound studio. One disadvantage is often actually the computer itself. The fan creates background noise and often the microphones that come with computer are extremely low end. At the very least try to find a good microphone if you want to record directly to a computer. The other disadvantage is you'll have to know how to use the software to record the files to your computer whereas with a tape deck most people know how to push record.

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Monitoring the recording

Examples of different level meters

It is a good idea to always bring headphones with you to monitor the audio. If the equipment you are using has the ability to monitor the recording, as with the Marantz tape decks or higher end video cameras, do so. If you can't do this, it is important to take test recordings before you begin your program recording to make sure that you are getting a recording with enough level to produce a clear recording without being too loud. When a track gets too loud it over saturates and clips, producing a very poor sound reproduction. The wireless microphone base stations also have a level adjuster so that can be used if no other method is available.

Levels

If the equipment or software you are using for your audio has level meters, you basically want to have the meters just brushing near the red without going into them. This is the 0 dB marker. Going over this will cause clipping and distortion of your recording.


What good is the video you shot if you can't understand what the subject is saying? You have probably seen a few home videos with either low fidelity audio which sounded tinny or noisy or which was too low in volume to make out. This isn't the videotape's fault. It is the camera's built in microphone. As noted above, higher quality audio compresses more cleanly. An added side benefit is that the more you can compress your audio, the more space you have for video, resulting in higher quality video!