Yes, a popular question and so I have done a video to try and explain/teach the best I could here:
https://howtoplaysaxophone.org/growling

It’s not that hard to do, maybe at first if you’ve never been there but follow along with the video and I’m sure you’ll get a good start on it. Let me know how you make out!

For me, this is where it’s at and so I love to share it. As beautiful and sexy as the sax can sound it just kills when dirty like that.