Some Basics on Microphones
Virtually all of the commonly used microphones employed with personal computers are termed electret microphones and operate by using a permanently electrically charged material which alters its voltage when deflected by sound waves. Generally such microphones include a very small "pre-amplifier" to boost this signal and which requires application of a small external voltage. The alteration of voltage caused by sound waves (an analog type signal) travels into your PC sound card or external sound card and is converted into a digital signal which is interpreted by your PC software. There are, in addition, a variety of microphone types based on the outward design of the microphone:
The issue of USB vs. Non-USB is an important topic. All microphones create an analog signal which needs to be converted to a digital signal for use with your computer software. The analog to digital conversion can happen outside of your computer (with either a converting device integrated into the microphone or with an independent converting device) or with your computer's on-board sound card. There are three main advantages to using a system doing the conversion outside of your computer:
The bottom line is that use of an external sound conversion device (adapter) is not essential but is highly recommended. Several microphones include built in USB devices, including the VXI Talk Pro USB 100 & 200, the Andrea NC 181 an 185 VM USB mics, the Speechware 6-in-1 microphone, the Samson Q1U, the Dictaphone PowerMic II, the Philips SpeechMic, and several of the wireless microphones such as the Sennheiser DW Office and Jabra 9470. If you purchase a standard analog microphone without an integrated USB sound adapter, we recommend purchasing an external USB sound adapter and interfacing your microphone to your computer with this adapter. You can read more about these devices near the bottom of this guide.