Ten percentage of the population in industrialized companies could benefit from hearing aids, and since the market remains 80% unpenetrated, new hearing aid companies and their financial backers see an enormous opportunity. But the hearing industry presents unique challenges compared to other medical device markets; the poor performance of past devices keeps people from buying hearing aids, as does the lack of reimbursement. Profitability is difficult for manufacturers to achieve, because manufacturing of the custom devices doesn't benefit from economies of scale. Finally, small companies have a tough time getting past the gatekeepers of the hearing industry--audiologists who have entrenched relationships with dominant manufacturers. New companies are entering the market with widely different approaches, some based on technology, some based on changing distribution channels. For some, the new approaches have clearly failed; others are embarking on new strategies that have yet to play out.