Nintendo Switch revised model has no sound or headset audio problems

The checks in more detail

If you are docked and have no sound from the TV, check the TV input, the HDMI cable and the TV's own volume, and set TV Sound to Automatic or, if it fails, to Stereo or Surround as your TV supports, which Nintendo documents. Remove and reseat the console in the dock. A console that has sound in handheld mode but not on the TV points to the HDMI path. For Bluetooth, remember that the Switch allows a limited number of Bluetooth audio devices and does not support microphones through them, and that audio over Bluetooth has some delay.

Forget the device in System Settings, Bluetooth Audio and pair again. A wired headset needs a four-pole plug, and a poor plug or dust in the jack causes crackle, so push it fully in and clean gently. If the speakers sound muffled, look for lint in the openings. A crackle at high volume is often a speaker rattle, and a game update or restart sometimes helps. Restart the console, install updates, and test a second game. If the sound is silent in every game and every output, with updates installed, ask Nintendo for repair.

Keep in mind that some games have a separate setting for headphones or speaker-only modes in their option menus. If sound lags behind the picture over Bluetooth, that is the normal delay of wireless audio, and a wired headset removes it. For a docked console, a TV that lists the Switch as a PC input may use a different audio path, so try the TV's other HDMI port and set the picture mode to Game, which also turns off processing that delays sound. After a firmware update, confirm that the Bluetooth device is still paired, since updates can clear it.