Many dash cams have a built-in microphone that can record audio in addition to video footage. However, laws regarding audio recording can vary by state or country, so it is important to check local laws to ensure compliance. In some places, recording audio without consent can be illegal, while in others it may be permissible as long as at least one party gives consent.
Some dash cams also have the option to turn off audio recording, which can be useful in situations where audio may not be necessary or desirable. Overall, the audio recording feature can add an extra layer of detail to the footage captured by a dash cam, which can be useful in certain situations such as providing context to an accident, or dealing with law enforcement.