Only option E reduced the overall A-weighted level to less than 90 dBA, and in fact, it reduced it to less than 85 dBA, the level at which OSHA requires a hearing conservation program. Thus, a worker could be exposed to the resulting sound level using option E for up to eight hours. The results of all of the other measures required limited exposure, according to Table 1. Untreated (and without hearing protection), the worker could be exposed to the 112-dBA sound level for only about 15 minutes during the day. Option B would allow the employee to be exposed to the 105-dBA sound level for one hour; Option C of 98 dBA for about 2 hours; and Option D of 91 dBA for about 7 hours. These times assume the worker is not exposed to other high noise levels; otherwise, these have to be accounted for, as well. The best solution depends on how long the parts tumbler is in operation and whether barriers or enclosures are practical. Other solutions may exist, as well. It's always best to have a qualified acoustician evaluate the problem and make recommendations.