How does surround sound work when there is only the two built-in speakers inside the TV?
It is called “simulated surround sound”. Using DSP(digital signal processing) technology built into the tv, certain audible cues such as phase, time arrival, delay, and frequency amplitude can be manipulated to create a surround sound effect out of just two speakers. The same way some receivers can create different soundfields like a small jazz club, cathedral, or large stadium for example. The drawback to simulated surround sound is that the sweet spot is extremely small so the effect only really works best for one person when they are right in the sweet spot which is smack dab in the center of both speakers. The technology is nothing new. My old Sony Tv from the early 90’s has simulated surround sound.