"Record audio" is the process of capturing sounds using a recording device. There are several other synonyms that you can use instead of "record audio." "Capture sound" is one such synonym that can be used to describe the act of recording audio. Another synonym is "audio recording," which refers to the actual recording itself. "Audio capture" is another alternative for "record audio," which emphasizes the process of capturing sound. "Sound recording" can also be used as a synonym for "record audio," to describe the process or the result. Lastly, "voice recording" is a synonym that specifically refers to recording audio of a person's voice. All these synonyms can be used interchangeably with "record audio" to add variety and clarity to your writing.