## 4 Discussion
Other research on traffic flow found rapidly alternating patterns of pass-by noise responsible for anomalies in annoyance [60]. Furthermore, changes in temporal and spectral signal features are other factors for an enhanced annoyance response found in laboratory and field studies [61; 62; 63]. These results are in compliance with neuro-biological and hearing research on the spectrotemporal filter mechanism of auditory attention [64; 65; 66]. If permanent changes of the temporal and frequency features occur the auditory system has difficulties to habituate and adapt--especially during nighttime. In her multicomponent approach [PERSON] [68] has summarized the main determinants of annoyance: the time-averaged difference between the loudness of the noise and that of the background noise (annoying loudness), the time-averaged difference between the sharpness of the noise and that of the background noise (called intrusiveness) and the distortion of the informational content. All those features were present in this case study. A notable annoying feature in this context was the large differences observed with the indicator sharpness--especially at higher speed levels. The control-study with terms from a comparable sized city revealed both: higher sharpness values and a wider spread in intensity for the \"new\" tramways in Graz (Figure 14). Particularly the high variability observed with the new tram type in most psychoacoustic indices underlines the difficulty of a straight interpretation of the acoustic situation based on a single indicator. Nevertheless, this observed variability in the emissions of the new tram (Variobahn) is the key for improvements by strict quality control. In Figure 14 the Variobahn shows a reasonable number of trips with sharpness values below two--even with speed up to 50 km/h. This means: when all new terms can be \"reprofiled\" to these levels, the noticeably would be significantly reduced. Currently, a small quality control study is conducted to shed more light on the possible general implementation of this feature. One has further to consider that due to atmospheric absorption effects the parameters sharpness and roughness behave differently with increased distance to a sound source compared to sound levels measured in dBA [69; 70]. Therefore, another substantial underestimation is to expect by using the A-weighting in cases like in Graz: you will notice the tram over longer distances and the affected population will be larger than estimated by classical indicators. A recent review [71] concluded, that commonly used weighting curves (e.g., Wm in Austria) do not correctly reflect annoyance caused by vibrations with multiple frequency components. Furthermore, recent evidence from exposure response curves [72; 73] suggest that the standards (e.g., [74] or [48]) may underestimate the potential effects on sleep during evening and night hours\". Unfortunately, the exposure response information in these studies used different vibration dose estimation parameters. To make this exposure-response information utilizable a mathematical conversion of the observed vibration values based on [48] into the one used in those studies (Wk-weighted RMS (m/s\({}^{2}\)) or VDV\({}_{b,2\mathit{thr}}\) (m/s\({}^{1.75}\)) and fast weighted, 0.125 s) was necessary. This concerned conversion from Wm-weighting to Wk-weighting, from slow to fast integration time and the calculation of the final overall dose (RMS or VDV). A full explanation of this procedure is provided in [75] and the resulting exposure response assessment is added as supplementary Figure A1 (annoyance) and Figure A2 (sleep disturbance). Based on these recalculations and considering upper 95% confidence intervals for the investigated effects, we could expect to have up to 15% highly annoyed and up to 25% sleep disturbed by the observed vibration values in Graz. These calculated effects are also comparable to those reported from the Cargo-vibe meta-analysis project [73].