VGA (Video Graphics Array) cables transmit analog video signals only and do not carry audio signals. When a user connects a laptop to an audiovisual system using a VGA cable, the lack of audio is due to VGA's inability to transmit sound. Switching to an HDMI (High-Definition Multimedia Interface) cable, which supports both audio and video signals, will most likely resolve the issue by enabling the transmission of sound to the audiovisual system alongside the video.