Sound quality study for a solenoid pump

Solenoid pumps are mostly used in the beverage machines, such as a coffee machine. The role of the pump is the extraction of the fluid from the water tank to the cup for the final user. The main drawback is the high level of generated noise, which is a critical factor influencing the overall experience of using a beverage machine. The aim of the project is to analyze and reduce the noise in the aspect of psychoacoustics. The primary objective of this research is to set an annoyance index to evaluate the sound quality which affect the acceptability of the generated noise. The annoyance index is calculated in terms of psychoacoustic descriptors, which are related to human perception of the sound. The optimization of the sound quality is then achievable by modifying the mechanical parameters in the pump. A set of measurements have been designed to observe the relationship between the noise sound pressure level and the vibration of the pump. A transfer function, which represents the relationship, has been obtained from the measurements. This transfer function can be used in the design of the pump to obtain a predicted sound pressure and eventually annoyance index as a sound standard.