This is most likely a problem with the Hz rate the audio for the capture card has been configured as. Please follow these instructions: On your main macOS Desktop, at the top left, look for the finder bar and click GoClick an empty space on your Mac desktop, or open a Finder window, if you do not see the Go menu Locate and select Utilities With the Utilities menu now open, locate Audio MIDI Setup and double click the icon Once inside of the main Audio MIDI Setup menu, locate the FHD Capture device, and click to highlight it Once highlighted, look for the drop down box next to Format and ensure that a 48,000Hz sample rate has been selected Once the correct sample rate rate has been selected, close out of Audio MIDI Setup and head into OBS With OBS open, locate the OBS listing on the top left of your macOS Desktop. Click it, and select Preferences Once the Preferences menu has been opened, on the left side locate and select the Audio option Inside of the Audio menu, please ensure that the drop down box next to Sample Rate has been properly set to 48KHz Once the drop down box is correct, click OK on the bottom right hand side of the menu, and restart OBS