This is a cone radius coming from the scatter gun, that is made of red eco. It makes a noise when you fire it, because when any red eco material device, weapon etc., it makes a noise of some sort of boing, or ding, like the precursor orb. The cone radius is close fire.
Amplifier is the first Eco Power Jak obtains in Stage 7 after being marooned on Brink Island by pirates. With this Red Eco power Jak can create a small red ball of energy. When Jak releases the orb, it floats away until it touches any obstacle. Shoot the orb to detonate it, creating a powerful explosion that damages all targets in range. Amplifier can be used to damage enemies and also to destroy cracked rocks and weakened walls. This is also a powerful weapon against boss enemies.