Besombes M., Goth Y.

In the framework of the R&D project LaMoNoV (LawnMower Noise and Vibration) dealing with noise sources ranking and characterisation in lawnmower machines, this paper presents a psychoacoustic approach based on jury assessments using, in particular, binaural audio-conform recordings under ISO-11094 standard measurement condition. The relationship between conventionally measured objective lawnmower noise and the general acoustic impression is derived from juries of experts, drivers and “neighbours”. A comparison is made between A-weighted ISO-11094 standard ratings and perceptive judgements. The obtained relationship is then tested against synthesised noise calculated through virtual acoustic prototyping, and specifically on the NST methodology (Noise Synthesis Technology). The prediction of the radiated noise, and related noise control recommendations, is achieved by means of a software tool which is fed by input data obtained from the components and their interaction. Two types of output data are available: synthesis noise in the form of third octave levels, and noise waveform reproduction. The NST does not work as an absolute predictive process, and thus requires experimental validation. Components are taken into account in a deterministic way, by establishing their detailed vibro-acoustic characteristics via measurement. In the present work on lawnmowers, selected components are the blade(s), the motor, its exhaust, the deck, the transmission system, ...