In high school, velocity is usually calculated by measuring distance and the corresponding time to cover that distance. But sound travels rapidly, covering about one meter in three milliseconds. This challenge can be met by using only a computer and an external microphone. A fixed frequency (1000 Hz) is fed into the computer's speaker and the external microphone monitors this wave train close to the speaker. Then the microphone is moved about a meter further away. This produces a waveform shift that, when compared to the original wave train recording, gives a precise measure of the number of wavelengths shifted. The flight time is this number times the period. Thus, the velocity of sound is calculated by dividing the distance the microphone was moved by this flight time. (Contains 10 figures.)