Subjective and instrumental evaluation of noise from a fuel metering pump of a parking heater

The noises produced by a fuel metering pump of a parking heater are evaluated both subjectively and instrumentally. Relevant parameters are control voltage as well as type and viscosity of the fuel. As expected, the radiated sound pressure level increases with control voltage and viscosity. Subjective evaluations of loudness are performed using the method of magnitude estimation with anchor sound. Two anchor sounds with rather different loudness are used. In addition, psychoacoustic evaluations using category scaling with symbols are performed. Instrumental measurements include determination of A-weighted sound pressure level as well as loudness measurements using DIN 45631/A1. The instrumental loudness measurements are in line with the subjective loudness evaluations. For practical applications is most relevant that when reducing the control voltage of the fuel metering pump by a factor of 1.3 the noise can be reduced by a factor of about 1.7 without compromising the functional capability.