This post’s title does match the article, but is misrepresentative. NASA is testing a plane that has a much quieter sonic boom. As far as I’m aware we don’t know how to not produce a sonic boom at all while going at those speeds (perhaps there will someday be a breakthrough here with sonic waves similar to how electromagnetic waves had the breakthrough of negative refraction indexes via metamaterials).
It’s not misrepresentative. The sonic boom is the coalescence of the pressure perturbations caused by the moving aircraft into an N shaped wave. When that coalescence can be delayed or prevented, there is no sonic boom to be perceived by people on the ground. The amplitude of the pressure pulse is much less relevant than the time over which that pressure peak is reached. When that time is stretched, there is no boom. That’s what the research discussed here is going for.