Diagnosis
The Dialogue Clarification feature boosts the center frequencies, but if your TV is outputting a surround sound signal (like Dolby Digital), the soundbar might be trying to play all channels at once, muddying the center voice channel.
How to Fix It
First, press the 'Dialogue' button on the remote once—you should see a small 'D' icon appear on the soundbar's display. Then, you need to check your TV's audio output format. Go into your TV's sound settings and change the 'Digital Audio Out' format from 'Auto' or 'Bitstream' to 'PCM'. This sends a simpler stereo signal that the dialogue enhancer can work on more effectively.
If That Didn't Work
Manually adjust the EQ. Press the 'Menu' button on the remote, go to 'Audio Settings', then 'EQ'. Try the 'Movie' preset, which is often tuned for clearer dialogue. You can also try manually raising the 'Treble' a notch or two.
Heads Up
The Dialogue setting works best at moderate volume levels. If you have the volume cranked very high or very low, its effect is less noticeable.