Crooner Bing Crosby knew a thing or two about sound. In 1947, recognizing that recorded music sounded better on magnetic reel-to-reel tape than on vinyl records, he invested in a company to develop equipment to record his radio shows. Soon, reel-to-reel tapes and recording and playback machines were a household craze. Now, as reel-to-reel tapes make a comeback among audio buffs, scientists are unraveling the secret of why some decades-old tapes are unplayable, while others retain their original superb audio fidelity.