## 2 Pass-By Noise Annoyance Evaluation Experiment
### Results
Aurally adequate analyses are more suitable for describing the perceived annoyance, quality, and pleasantness of household appliance sounds, medical equipment sounds and auditory signs [12; 13; 14; 37; 38]. To describe the perceived characteristics of car pass-by noises, the psychoacoustical properties of the noises were calculated using different perceptual models. Figure 6: The relationship between perceived annoyance ratings and the developed annoyance index, which is based on psychoacoustical properties. (Red dots: ICE cars, green dots: hybrid cars, and blue dots: electric cars). Figure 7: (**a**) The relationship between perceived annoyance ratings and the TETC index. (**b**) The relationship between perceived annoyance ratings and sharpness. A panel consisting of five acoustic experts and five naive participants with no technical background or specific acoustic knowledge listened to car pass-by noises and discussed their annoyance levels. The signal properties of the stimuli were analyzed using Short-Time Fourier Transform (STFT) and sound pressure level versus time analysis. The frequency content over time and several level properties, such as L\({}_{\text{Aeq}}\), L\({}_{\text{max}}\), L\({}_{\text{AF}}\), L\({}_{\text{AS}}\), etc., were determined. Psychoacoustical properties, such as loudness, tonality, roughness and fluctuation strength, were selected as proper indicators for the annoyance characterization, taking into account the panel discussion, signal analyses of the car pass-by noises, and annoyance ratings from the listening experiment. Although sharpness was also considered as a possible indicator, the analysis results (von Bismack model [39]), which can be found in Figure 7b, showed that the sharpness differences of the pass-by noises were very small and not very consistent with the annoyance ratings. An index was developed to account for the relationship between the annoyance ratings and the calculated psychoacoustical parameters. In this index, the Zwicker model was used for the calculation of the loudness (according to ISO532-1 [40]), the model from ECMA-74 was used for the calculation of the tonality, the Sottek model was used for the calculation of the roughness [41; 42; 43], and the Terhardt model was used for the calculation of the fluctuation strength [44]. The weightings of the psychoacoustical properties given in Equation (1) were determined considering the feedbacks during the panel and the relationship between the annoyance ratings and the results of the psychoacoustical properties. An important criterion was the differences in the numerical values of the psychoacoustical properties. For example, the numerical value of the loudness of car pass-by noises is 40 to 100 times higher than that of the tonality value. Another important criterion was to iteratively check if additional psychoacoustical property improves the coefficient of determination. If so, it was important to find which weighting delivers the optimum result without neglecting the feedback of panel members. The weighting of tonality gives tonality slightly lower importance than loudness in the equation. The numerical value of the loudness of pass-by noises is 10 to 20 times higher than that of the roughness value. Consideration of roughness in the equation improved the coefficient of determination. However, the contribution should be limited because of the achievement of an optimum coefficient of determination. The numerical value of the loudness of pass-by noises is 500 to 1000 times higher than that of the fluctuation strength  
Figure 8: The relationship between perceived annoyance ratings and the annoyance index, which is the combination of the psychoacoustical properties from the Equation (1) and the TETC index. (Red dots: ICE cars, green dots: hybrid cars, and blue dots: electric cars). value. Consideration of fluctuation strength in the equation also improved the coefficient of determination. However, the contribution should be limited because of the achievement of an optimum coefficient of determination.