I just got a new Onn Roku TV (model 100012585), and the audio on all apps make the background noises louder that any speech. Specifically during sports games, the commentary is very quiet compared to the other noises that sound muffled (but still loud). It sounds like the type of sound you would hear from a surround sound system, but I have no secondary audio devices (literally just the power chord plugged in).
I have called twice, done factory resets, changed sound settings and sound modes, to no avail.