This includes USB turntables, USB cassette decks and external USB audio input/output adapters. Does anyone have any idea why I can't see it, and/or how I can navigate to it? Also, any ideas why it would look different on this computer? Could I have an older version of Audacity on my MacBook? If someone could confirm whether the latest version of Audacity behaves more like the description from my MacBook or my Mini, that would be helpful. On Mac OS X using current Audacity or legacy 1.3.12 or later, the following procedure should get sound from the USB audio input device into Audacity. I checked in the View menu, and plenty of toolbars, including the selection toolbar, are checked.
In fact, I don't have any toolbars - I have a handful of controls that appear in toolbars on my MacBook, but on my Mini they're just all there in the main window, and it's not nearly all the controls that should be there. I recently got a Mac Mini for the office and downloaded Audacity, and I can't interact with that toolbar.
When I use Audacity on my MacBook, there is a selection toolbar that I can interact with, which provides information such as the timecode of the current selection start and end, among other things.