[quote=@TheWindel]
<Snipped quote by Lacroix>

Can you elaborate a bit more on this. By "magical effects", does that include the magical powers of other Magical Girls?

[/quote]

The magical sound waves disrupt and erode any form of conjured magic in their path, making it harder for them to mantain their form. As such, Nightmares would be slowly weakened and damaged, projectiles made with magic would lose a bit of strength and objects created with magic would be damaged little by little until they break, unless one invests energy to help them mantain their form.

Against other magical girls it's loud and disorientating but, unless they're caught by it by prolonged periods of time, there's no real damage to them, their arms nor their emblems.