A hearing aid is an ultra miniature electroacoustical device that is always too large. It must amplify sounds a million times but bring in no noise. It must operate, without failure, in a sea of perspiration, a cloud of talcum powder, or both. It is a product that one puts off buying for ten years after s/he needs it, but cannot do without for thirty minutes when it has to be serviced.
By Sam Lybarger