It’s hard to say because people usually use the term “whistling” instead of “hissing” to describe feedback. But I guess it depends on what the OP meant by “hissing” here. Usually, if the directionality settings is set to Fully Directional to focus on the front beam forming only, it will cause a roll-off frequency at the low frequency end, in which the hearing aid automatically compensates for it by raising that low end to make up for the roll-off. But by doing so, it will raise the floor noise along with it. If the user has good low frequency hearing and is in a quiet environment, sometimes this floor noise can be heard as “hissing”. One way to avoid it is perhaps to not force the Intent Directionality Settings to “Fully Directional”, but leave it in “Neural Automatic” to see if that helps. At least that would be the first thing I would try, if indeed the Directionality Settings is set to Fully Directional like I suspect it is.