Solid Hardwood, Engineered and Laminate Flooring - Hardwood floors and OSB subfloors

I recently installed hardwood floors in three rooms on the second floor of my townhouse. After much research, I tackled the job myself and it looks great. However, there are popping sounds when I walk across the floor. I have determined that the OSB subfloor is the culprit as it does not hold the nails as well as plywood. I have read that many installers will not work with OSB and now I know why. I did research the OSB product on the manufacturer's ( Weyerhauser ) website and it was rated for hardwood applications. I suppose I will have to live with the slight nuisance of popping sounds or pull up the floor and do it over. But my question is: I want to also put hardwood in my living room. Should I install 1/2 inch plywood ( and what kind )over the OSB subfloor to provide better holding for the nails or should I tear up OSB and put 3/4 inch plywood instead. Any advice will be appreciated. Thanks.