Duct muffler or longer ducting

I exaust my grow room to outside my house. The flowering room is in the basement.

Currently my setup is carbon filter->light->inline->outside house

My problem is that I want the exaust to be quieter on the outside of the house.
My other problem is that my inline is only 8ft away from the exaust hole.

What would be the most effective way of cutting back on excessive noise outside? I'm not worried about noise in the grow room, but only outside.

I use a 6" inline hydrofarm fan.
Id like to believe that the noise I hear outside the house is air flow only but someone tell me differently and I'll listen. I use 6 flex ducting, with no bends in it. Straight from grow to to outside.

Do u use insulated ducting? If not that'll help cut down some of the noise. I'll admit I'm not an expert on sound control since its not an issue for me but I think there is a sticky thread discussing it. u said ur in a basement tho, is ur water heater in the basement by chance? Cuz if it is u could tie ur exhaust into the water heaters exhaust n it would vent thru the ducting out the top of the roof. Then u could close ur current exhaust hole up, or use it as an intake, whatevers clever.
That's how I have mine set up.

easiest most effective way is to get a duct muffler. An other way is to increase the size of exhaust line at the exit of the grow room and use some larger insulated flexible ducting and then bring it back to 6" at the house exit. The increase in volume disrupts sound waves.