Constant honking!

Hi guys I really hope you can give me some advice.

My 3 year old lop Ollie started honking about 2 years ago. It was quiet at first and he only did it occasionally but it quickly got worse. Thinking it was a hormonal thing, I had him fixed. This made no difference. I then took him back to the vet who gave him the once over. Ollie was honking too loudly for the vet to listen to his chest so gave me some medicine to give him just in case his chest wasn't clear. The medicine made no difference and the vet saw him again and put it down to bad habit. I know lots of people's rabbits are vocal but ollie is rather difficult to live with. He regularly has to be put in another room because you can't hear the tv over him. He gets plenty of exercise both inside and out of the house, he is stimulated and I spend lots of time with him grooming etc. the noise is just a louder version of the soft grunt/honk that many bun's do and doesn't seem to bother him at all and he is perfectly happy within himself so I'm very confused. Sometimes he'll have a few days where he hardly makes any noise..quickly followed by day after day of constant noise. He has no medical history of note other than successfully treated head tilt at 10 weeks old. None of my 3 previous rabbits have made so much noise : / has anybody had a similar experience with this kind of constant honking?? Any suggestions and advice would be so great! : ) xx

Also worth mentioning I have changed bedding three times and its definitely not an allergy that's giving him noisy breathing or anything : )

My rabbit Mo has been extremely grunty since we got him. He as been to the vets about it & the vet said that he has a more active pasturella gene than other 'non grunty' rabbits & told us its nothing to worry about

He is happy healthy bunnie who wouldn't be the same without the odd noises he makes

I don't really know but had my girl spayed 18 months ago, she is an older rescue bunny and she honks all the time when she eats. She never used to. She basically honks when she is happy. She has no health problems.

Nutmeg is VERY vocal too. My vet says she's got lung damage from a previous infection (we're about her third home). There's not much we can do except watch it for it getting any worse.

Thanks guys. So long as I know he's happy and comfortable then that's all that matters. Was always in the back of my mind that there was something wrong and the vet had missed something but he's obviously just one of the grunty ones