Copy all audio files from a folder recursively, while leaving directory structure intact using PowerShell

I am trying to move all .mp3 and .wav files from one folder to another, while leaving the relative path of the files the same.

Imagine a directory structure that looks like this:

DirA
  subfolder_1
    song.mp3
    subfolder_subfolder
      dj.wav
  somefile.txt
  kittens.jpg
  subfolder_2
    txt.png
  bass.wav

I want to copy the files from DirA into DirB, so that DirB will look like:

DirB
  subfolder_1
    song.mp3
    subfolder_subfolder
      dj.wav
  bass.wav

Any folder that does not contain any audio files should not be copied over.

I could write a Python or Node.JS script for this or something like that, but I was hoping there would be an easier solution using just PowerShell.