(Bloomberg Businessweek) -- When Brandon Sawalich started at Starkey Hearing Technologies in suburban Minneapolis, he was 19 and there were about 70 companies worldwide making hearing aids. That was 1994. His job was to clean the ones mailed in for repair or, occasionally, as returns, because the user was dead and no longer required them. Today, Sawalich is 43, there are five companies, and he’s president of Starkey, which employs 6,...