|Jean LeLoup & Bob Ponterio
Your microphone should be suited to your recording equipment and to the sort of recording you are doing. Poor quality equipment or a noisy environment will introduce noise into your recording, interfering with the signal that you are trying to capture. Basically, signal is what you want, noise is the sound you don't want. An omni-directional mic picks up sound from all directions and is good for recording background noise, music from several directions, or several people talking. A uni-directional mic is pointed at the sound coming from a single source - one speaker, one instrument, etc. Clip-on mics can do a great job recording individuals in conversations because they are placed so close to the person's mouth, but if you have more than one or two participants, you may need to think about mixing sounds from multiple mics to control different sound levels. Table mics are nice for several people sitting around a table but will pick up the sound of someone touching or bumping into the table, shuffling papers, etc., so subjects need to take care if you use these. Microphones that are built into a tape recorder, camcorder or computer tend to pick up machine vibrations from motors (more noise) and are difficult to place close enough to a subject. A long microphone cable may act as an antenna that could pick up static from fluorescent lighting or even a local AM radio station.
If a microphone's specifications include "signal to noise ratio", a high signal to noise ratio will sound best. Another way to improve your microphone's sound is to use a pre-amp (see below).
The sound card in a computer can create sound, process sound from input sources, and send sound to output destinations. A sound recorder may capture sound from a microphone (mic in) or from an audio device (line in). It is possible to control which source will be used by opening the volume control. This utility controls the output or playback volume of a number of devices (microphone, line in, CD audio, midi, wave, etc.).
Controls in Windows XP are similar.
By resetting the options/properties from playback to recording, the input source (mic, line in, CD, midi) may be selected. If you are recording from a microphone, you may need to check that the mic is selected here, that the mic volume is adequate but not too loud, and, perhaps if needed, that the microphone is boosted (under Advanced properties). You have to play with it to see what works for your current recording conditions.
In Windows 7, the microphone levels can also be adjusted.
Pre-Amp: The quality of microphone inputs can vary enormously from one computer to another. If you need better quality recording from a microphone, it may be worth investing in a pre-amplifier that will amplify the microphone input. This gives you more control over strength of the signal that your computer receives. The sound card in your computer probably has a pretty cheap amplifier for the microphone. A pre-amp will do a better job boosting the microphone's signal.
The output from the pre-amp would then be plugged into the computer's line-in jack (rather than the microphone input jack). When using a pre-amp, you may need to be careful of clipping in both the pre-amp and the sound card.
Microphones may be unidirectional (best at capturing sound coming from a single direction) or omnidirectional (captures sound coming from all directions).
Amplified Lavelier mics clipped onto the speaker's clothing have the advantage of getting more of the speaker's voice than background simply because they are close to the speaker.
For quick interactive communication, a simple monophonic mic & earphone are very easy to set up without wasting time.
One of the oldest ways to make a recording using Windows' built-in tools is to open the entertainment accessory, (start / all programs / accessories / entertainment) Sound Recorder. Click on the red recording dot to begin. Save the file in .WAV format using File / Save, and be sure to select File / New to begin another recording from scratch. Under the menu (Edit / Audio Properties / Customize) it is possible to select a particular frequency and resolution other than the old default 22,050 Hz 8 bit mono. The best frequency and resolution are always a tradeoff between quality and size. Music is more demanding than voice. We recommend using at least 22,000 Hz 16 bit for voice recording for projects in this class. However, we absolutely do NOT recommend using Sound Recorder at all! You can download free software that is infinitely better.
Sound Recorder from Windows 7
A much greater degree of control and more extensive features for manipulating sound files are available in sophisticated sound applications Adobe Audition, and Sound Forge. The main features needed are selecting and cropping a sound as you might a photo, normalizing a sound as you might adjust the brightness of a photo, and saving the sound in a variety of formats commonly supported by multimedia applications and Web browsers.
The Edit / Trim menu will crop (or trim) a selected portion of the sound. File / Save as... offers a wide variety of options including .AU .WAV, .RA (RealAudio), and .Mp3. Mp3 format is widely accessible and uses an excellent compression CODEC (compression-decompression) to make file size smaller while maintaining very good sound quality.
Audacity is a good quality, free sound editing program that has all the features you are likely to need. http://audacity.sourceforge.net/
Sound editing will be covered in a later lesson.
There are also other low cost programs available for sound editing that will do a fine job for most of your needs.
AUDIO RECORDING AND EDITING FOR THE WEB AND IPODS:
Equipment for Audio Recording of Speech:
Audacity 2.0 Manual
Audio Basics from Audacity: Tutorials
Editing and existing file: http://manual.audacityteam.org/o/man/tutorial_editing_an_existing_file.html
Your first recording: http://manual.audacityteam.org/o/man/tutorial_your_first_recording.html
Audacity Tutorial for Podcasts
Sound Advice: 10 Tips for Better Audio Gathering:
Sensitivity of the Human Ear:
Sound recording: Microphones:
A Primer on
Record Your Own Radio Documentary:
How to Create Your Own Podcast - A Step-by-Step Tutorial