Connect the microphone to your computer and open the sound editing software. Set up the microphone in an area where there is little noise interference, where you will be able to record the sound of a person's voice clearly because you will be listening for tiny differences in the pronunciation of a word.
Hit the "Record" button and have someone, or yourself, speak into the microphone. The best method to record a voice for the purpose of measuring voice onset time is to repeat a word with a hard consonant and vowel back to back such as "stop," "spot" or "dot." Press the "Stop" button when finished.
Open up the newly recorded file in your sound editing program. Play the file and use the "Zoom" function to zoom in on one clear example of the word. Continue to zoom in until you see the sound wave for the part of the word where the speaker transitions from the consonant to the vowel.
Listen to the file several times and note the time, in milliseconds, that the consonant sound ends. Continue to listen to the file and place the marker on the exact point at which you begin to hear the vowel sound. The amount of time in the gap between the two is the voice onset time for this particular word.