October 16, 2007 | Written by: Acentech

Amplitude Modulation: Wow, Wow Sounds Impair Sound Quality

A common issue in product sound quality has to do with the degree of modulation of a sound – that is, even if the sound itself is not particularly loud, the presence of an unsteady component in the sound can make it more noticeable. This was the case for a manufacturer of axle-transmission assemblies, who was receiving feedback from some end-users, complaining of “gear whine” coming and going every 2 to 3 seconds during vehicle coasting. In addition to the annoyance factor, this sound also made users suspicious of the quality of the transmission in general. It was eventually determined that only some of the axles behaved this way, and that it would be desirable to “catch” these axles before they were shipped. A procedure was therefore developed to automatically determine the degree of modulation present during a coastdown run of an axle on a test stand, using vibration measured on the transmission housing.



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