Some audio adapters come complete with a microphone, but most do not. You'll need one to record your voice to a WAV file. Selecting a microphone is quite simple. You need one that has a 1/8'' minijack to plug into your audio adapter's microphone, or audio in, jack. Most microphones have an on/off switch.

Like speakers, microphones are measured by their frequency ranges. This is not an important buying factor, however, because the human voice has a limited range. If you are recording only voices, consider an inexpensive microphone that covers a limited range of frequencies.

An expensive microphone's recording capabilities extend to frequencies outside the voice's range. Why pay for something you won't be needing? If you are recording music, invest in an expensive microphone, but be sure that your audio adapter can do justice to the signal produced by the microphone.

A high-quality microphone can produce mediocre results when paired with a cheap 8-bit audio adapter. Your biggest decision is to select a microphone that suits your recording style. If you work in a noisy office, you might want a unidirectional microphone that will prevent extraneous noises from being recorded.

An omnidirectional microphone is best for recording a group conversation. Some audio adapters include a microphone. This can be a small lapel microphone, a handheld microphone, or one with a desktop stand. If you want to keep your hands free, you might want to shun the traditional handheld microphone for a lapel or desktop model.

If your audio adapter does not come with a microphone, see your local stereo or electronics parts store. Be sure that any microphone you purchase has the correct impedance to match the audio adapter's input.

If you're using software such as Dragon Naturally Speaking, IBM Via Voice, Philips FreeSpeech, or other voice-recognition software, use the microphone supplied with the software or choose from alternative models the software vendor recommends. Run the microphone setup program again if your software has trouble recognizing your voice.

Some newer models feature a battery pack to boost sound quality; be sure to check the batteries and replace them to keep recognition quality high. If you're talking but your voice-recognition or recording software isn't responding, check the following:

• Incorrect jack. It's easy to plug the microphone into the wrong jack. Try using a magic marker to color-code the microphone wire and jack to make matching up easier.

• Check the recording volume in the mixer control. This usually defaults to Mute to avoid spurious noise.

• Make sure the microphone is turned on in the voice-recognition or recording software. You must click the Record button in recording software, and many voice-recognition programs let you "pick up" the microphone for use or "put it down" when you need to answer the phone. Look for an onscreen microphone icon in the Windows System Tray for fast toggling between modes.