To unlock the silence the scientist trophy in Crash Bandicoot 4 you must destroy a green test tube from N.brio. At the beginning of the level (Give it a Spin) you will find one.

This trophy is located on MAP: The Hazardous Wastes
LEVEL: Hit The Road. You need to attack 6 barrels that produce a sound. 3 of them are right at the beginning of the level. The other three are close to the bonus path.

To unlock the Megaphoning in it trophy in Crash Bandicoot 4 you must destroy N.Gin’s Megaphone speaker! It’s located shortly after the start of “A Real Grind”in the The Hazardous Wastes map.