I could be wrong, it's a bit difficult to tell from just that clip, but it almost sounds like electrical interference.
By any chance, are your speakers connected via an analog connection rather than a digital connection? If you have the option available to you, try as a test connecting to speakers via a digital connection to see if it still happens. Another option would be to try playing audio through your monitor as a test, if you are not doing so already, but make sure to use a digital connection such as playing the audio through your HDMI or DisplayPort connection.
