There are several possible causes of this problem:
The microphone isn't close enough to pick up your voice. Make sure that the microphone is positioned close enough and that you're speaking directly into it.
The microphone is muted. Some microphones have an external control for muting. Make sure the mute control is turned off.
The microphone input level is too low. Make sure the microphone input level is set properly.
Speech Recognition is available only in English, French, Spanish, German, Japanese, Simplified Chinese, and Traditional Chinese.
Open Sound by clicking the Start button , and then clicking Control Panel. In the search box, type sound, and then click Sound.
Click the Recording tab.
Double-click the microphone that you use for Speech Recognition.
Click the Levels tab, and then use the slider to set the input level for your microphone.
The microphone connections aren't properly attached. Make sure the microphone wires are intact and unbroken. Make sure the connections aren't loose and that they fit snugly into the computer.
A different microphone is selected for use with Speech Recognition. If you have more than one microphone installed on your computer, the wrong one might be selected for use with Speech Recognition. Make sure you're using the microphone selected for Speech Recognition.
Select the microphone you want to use with Speech Recognition, and then click Set Default.
A voice profile hasn't been created. You can train your computer to better understand you by creating a voice profile that your computer uses to recognize spoken commands.
Open Speech Recognition by clicking the Start button , clicking Control Panel, clicking Ease of Access, and then clicking Speech Recognition.
Click Train your computer to better understand you, and then follow the instructions in the Speech Recognition Voice Training wizard.
Speech Recognition doesn't recognize the commands you're using. Familiarize yourself with the commands that Speech Recognition recognizes. For more information, see Common commands in Speech Recognition.
Check the information that came with the microphone for additional troubleshooting information. Common troubleshooting steps include making certain the sound card for the computer is properly installed and that the correct drivers are available.