Many people are exposed to sounds made by heating, ventilating, air conditioning and refrigeration equipment. These sounds can have a rich harmonic structure attributable to various rotating components: e.g., fans, motors and compressors. There are also broadband components arising from air motion, turbulence and fluid pulsations. Both sound components are also usually modified by acoustical and structural resonances. The design or modification of equipment to optimize sound quality is challenging because of the number of source and path mechanisms affecting the sounds, and also because there is not a comprehensive model that can be used to translate measured sounds into predictions of how people will respond to them in particular situations. A combination of accurate sound prediction and sound assessment tools can be used to explore different design options. The methodology described here is being used to create a broad set of sounds that can be used to develop a sound quality model for HVAC&R equipment noise. A technique to decompose sounds into tonal and broadband components and approaches to modifying the sounds to independently control sound quality attributes such as loudness, tonality, roughness, fluctuation strength and spectral balance are described.
Sound quality, Signal modification, HVAC noise
Acoustics and Noise Control
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