A process and apparatus for selecting or designing a product, such as a muffler, having a sound output which is less stressful or more pleasing. The process includes the steps of sensing at least one physiological response of a subject (21) while the subject listens to an initial sound output, repeating...http://www.google.de/patents/US6584346?utm_source=gb-gplus-sharePatent US6584346 - Process and apparatus for selecting or designing products having sound outputs
