New Procedure For Loudness Assesment and Noise Attenuation of Ventilation Kitchen Range Hoods
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The Home Ventilating Institute (HVI) created a standard to specify the procedure for sound quality testing of mechanical ventilation equipment. This standard contained a procedure for performance, reliability, and accuracy based on a full assembly loudness assessment. This thesis provides a new generic component loudness assessment procedure that can be utilized to identify and reduce the noise radiating from kitchen range hoods based on an individual component loudness assessment. With these evaluations, design improvements are implemented to help reduce the outgoing noise from the range hood that may cause hearing loss or high stress. Four different range hoods were tested across the 24-1/3 octave frequency bands using the new component loudness assessment procedure. The kitchen range hoods tested include two centrifugal-flow fans and two axial-flow fans for ventilation. Each range hood includes basic component design differences in the damper, grille, and enclosure. The results show that in all but one case the damper caused an increase in the overall loudness by 10% at high speed and as much as 70% at low speed. In addition it has been observed that the addition of the grille can either reduce the loudness or increase the loudness depending on design features. Using the information gathered from the component loudness assessment, practical low-cost noise attenuation techniques are formulated and implemented in order to reduce overall loudness. The primary goal of noise attenuation (or noise reduction) is to diminish the overall loudness to a comfortable level. Using the techniques formulated, vibration and aerodynamic induced noise have been reduced across all speeds of the range hood by as much as 15%. The greatest reduction was observed at high speed with a reduction of 2.17 sones, while mid and low speed were able to archive a reduction of 0.89 sones and 1 sone respectively. The new procedure gives improved insight into individual components contribution to overall loudness, and provides better intuition on how to reduce the outgoing noise. A reduction in noise should improve the sound quality indoors and have a positive effect on consumer health and quality of life.
Gomez, Antonio Valdez (2015). New Procedure For Loudness Assesment and Noise Attenuation of Ventilation Kitchen Range Hoods. Master's thesis, Texas A & M University. Available electronically from