Echo Blast

The Echo Blast is the ability to generate an extremely powerful and highly destructive scream of energy from one's vocal cords and mouth, accompanied by a high-piercing sound. Though it does no physical damage to a target, it's mostly used to disorientate them, making them easier to strike.

Other World Series
In the Other World Series, this is one of the most basic abilities taught to students. Hero found this ability to be of great help whenever dealing with multiple enemies at once and he's in need of escape or at least a minor rest period.

Hero: The Guardian Smurf stories
In the HERO: The Guardian Smurf story series, Hero rarely used this ability upon his return from Other World. His counterpart, Wonder, and their daughter, Saviour, primarily use this ability as a form of self-defense or at least to escape from any threats.

Trivia

 * This ability was inspired by the ability known as Ghostly Wail from the Danny Phantom animated series.