Sound quality investigation of notebook inlet grilles

摘要

An inlet grille on the bottom skin of a notebook, just below the blower, is required according tosafety guidelines for a direct inlet. The aim of this investigation is to perform an initial study tominimize the generated noise from an inlet grille/blower combination using the sound qualityparameters to develop acoustically preferred inlet grille design guidelines. All of theinvestigated grilles have an overall circular shape to match the inlet opening on the blower, withslot openings that are either straight (jail-bar) or circular. Three slot widths (1 mm, 2 mm and 4mm) for both the jail-bar grilles and circular grilles were investigated. The sound parametersstudied were the sound pressure level and the sound quality parameters: loudness, tonality andsharpness. All grille shapes show an increasing level of sound pressure, loudness, tonality andsharpness as the distance between the grille and rotor decreases. The two coarser jail-bar grilles(2 mm and 4 mm) generate significantly higher values of sound pressure level, loudness andtonality for small grille/rotor distances. In general, the circular grille shape shows better soundquality characteristics than the jail-bar grilles, where the smaller slot size of 1 mm is preferred ofthe grilles investigated.