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In today's urban environment inhabitants are permanently exposed to elevated noise levels, which are mostly dominated by traffic noise. The current electrification of vehicles might affect the traffic noise in city centers. The aim of this work was to determine the pedestrian reaction, the annoyance and the warning effect of electric vehicle sounds. For this purpose the differences in the perceived annoyance, warning effect and detection time were investigated with perception studies. Furthermore the sound level of a full speed-scaling of an approaching vehicle starting from 0 km/h at the critical distance is nearly 10 dB below the level of a constant speed of 10 km/h. Therefore variants of electric vehicle sounds were generated, in which a constant level is used below 5 or 10 km/h. The results show that the change of the speed-scaling influences the detection time enormously. In this study, Artificial neural network (ANN) is used as an indexing tool to imitate subjective perceptions, because in some further work the results of artificial neural networks show great correlation with the assessments of subjects in listening tests. Through the use of ANN, a flexible model can be developed which can predict the annoyance or the warning effect of future electric vehicle sounds.

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Household appliances and their sound quality are important for our daily life quality. However the appropriate characterization of their sound is a difficult task. Not only product users but also manufacturers can profit from a sound label which characterize the perception of the customers. The purchase decision-making process according to acoustic criteria will be supported by such kind of label. In addition, a label and its components give orientation to the manufacturers during their product development process. Essential aspect for such kind of label is that it should represent the perception of the customers. Therefore psychoacoustical properties, e.g., loudness, sharpness, roughness, tonality, etc., are advantageous for characterization purposes. It would be beneficial to combine these psychoacoustical descriptors into a sound quality label, which is easy to understand. The authors have developed several sound labels for household appliances based on psychoacoustic properties. These sound labels are the result of the listening experiments which were conducted with potential customers. In this paper, various aspects of these investigations are summarized, extended and discussed.

The first aim of this paper was to determine the variability in the signal characteristics and psychoacoustic data of canister-type vacuum cleaners. Fifteen vacuum cleaners with different sound power levels, provided by the manufacturers, were selected as test units to calculate their acoustic and psychoacoustic parameters. The selection of the devices was based on an even distribution of the reported sound power levels. The investigated variability in the acoustic and psychoacoustic parameters on different vacuum cleaners was discussed to derive the common characteristics of canister-type vacuum cleaner noise. The derived common characteristics were compared with the those in the available literature on the noise generation mechanisms of vacuum cleaners. Based on these characteristics, prototypical vacuum cleaner noise was defined. The second aim of this paper was to understand the annoyance perception of vacuum cleaner noise. Annoyance assessments were obtained from two sets of listening experiments. The first listening experiment was conducted to find the correlates of annoyance evaluations. Loudness, sharpness and tonal components at lower and higher frequencies were found to be dominant correlates of vacuum cleaner noise annoyance estimations. In the second listening experiment, a possible interaction between loudness and sharpness was investigated in different listening test methods. The selected loudness and sharpness values for this experiment were consistent with the observed ranges in the first part. No significant interaction between loudness and sharpness was observed, although each separately correlated significantly positively with annoyance.