What is the significance of the primo passaggio in vocal training and how does it impact a singer's overall performance?

The primo passaggio is an important vocal transition point where the voice shifts from chest voice to head voice. Mastering this transition is crucial for singers as it allows for a smooth and connected vocal range. It impacts a singer's performance by enabling them to sing with greater control, flexibility, and power across their entire vocal range, leading to a more polished and expressive performance.