Diagnosis
This is almost always a software glitch related to the TV's audio processing, often tied to a feature called 'Auto Volume' or an HDMI setting conflicting with the app's output.
How to Fix It
Start with the audio settings menu. Press the Home button, go to Settings > Sound > Expert Settings. First, turn off 'Auto Volume' (this tries to normalize loud commercials and often glitches). Next, change 'Digital Output Audio Format' from 'Auto' to 'PCM'. This is a more universal format that apps handle better. Finally, go back and ensure 'Sound Mode' is set to 'Standard', not 'Adaptive' or 'Game'. Restart the TV after making these changes.
If That Didn't Work
If the dropouts persist, it could be a Wi-Fi interference issue, as the TV uses the same wireless band for streaming data and audio. Try switching the TV's audio to an optical cable output if you're using a soundbar, or temporarily connect the TV to your router with an ethernet cable. If the dropouts stop, you've confirmed it's a wireless congestion problem.
Heads Up
Don't overlook your HDMI cables if you're using an external device. A cheap or damaged HDMI cable can cause intermittent audio handshake failures. Try a different, certified high-speed HDMI cable.