It could just be the nature of the beast.  We have 2 furnaces in our house, the main one in the basement and a smaller one upstairs just for two rooms there  Same brand, same basic design except the big one is closed combustion with a fresh air pipe to outdoors, and the small one draws combustion air from the room.  The kids nicknamed the one upstairs the dragon because  it is so noisy.

OK, I just went back and reread your post.  If I understand correctly it does not do it all the time?  That tells me 2 things.  1, yes, something isn't right and 2, it may be a bear to figure out.  My main furnace was pulled from a customer's house because it kept doing weird things. We finally figured out the problem, but ended up replacing it with a new one under warranty to satisfy the customer (replaced by the boss, not the furnace mfg). 

How old is the furnace and is this a new development? There are a couple possibilities but if your furnace guy is any good at all he should have caught it.  After re-reading what you said it sounds like it is burning at the orifices themselves instead of outside the burners like it should.  That WILL sound like a jet engine. However it should also be quite apparent from looking at the furnace operating.

Oh, back to mine. The original complaint was it blew cold air for a long time before any hot air came out.  The problem has to do with the flame transfer between burners. It would go through the ignition cycle, but the flame would not transfer across all the burners. The flame sensor would shut it down, it would purge and recycle. There would be enough heat to cause the air circulating fan to kick on, blowing cold air around the house. The second time it would light perfectly and warm air would come out.  It was a real pain to figure out because you had to be observing it cold to get it to misbehave.  We ended up putting a second ignitor on it so the burners were lit from both sides.

We believe the burners were manufactured just ever so slightly "off" and would not transfer the flame.  By the time it had tried, failed, purged, and recycled there was enough heat transferred to cause the gap to open or close just enough it worked.

I told you that long story to illustrate this.  It may be a very simple problem that is very difficult problem to diagnose.  It may be as simple as a spiderweb in a burner, it may be poor machining of the orifices (however to be honest that is a new one on me), it may be the burners have seen enough use they need replaced, on and on.  But after pondering on it (this reply has taken me half an hour so far) it sounds to me like the flame is burning in the orifices.

If it has burners with an air mix adjustment I'd try closing the air down slightly.  SLIGHTLY! You don't want to shut the air down so much it starts sooting.  That is a whole different problem you don't want to address.  My guess is your furnace guy's next move is going to be replacing the burners.