This video is about singing better by optimizing your voice's resonance.
The resonance in your body is determined by the cavity that resonates. Relax your voice box and let it resonate with an open space. The bridge-to cross the bridge, use the sound "Na". Na, na, na, na, na, na, na. It increases the vocal volume. EQ voice-Eq affects the highs and lows in the voice. It give s the voice more texture and volume. The viewer learns techniques to optimize the voice's resonance.