## 3 Experimental Investigation on Different Kinds of Earthmoving Machines
### Listening Tests and Subjective Annoyance Scores  
The six binaural noise recordings were organized in pairs, and all pairs were arranged in a random sequence according to the digram-balanced Latin square design to avoid any sequence effect. In addition, each sequence included at least the repetition of the first pair of the sound stimuli for checking purposes. Thirty-five normal-hearing subjects (28 males and 7 females) were involved in the listening test. Fifty-eight percent of the subjects were aged less than 29 years, with 32% less than 50 and only 10% over 50. The group included experts of earthmoving machines (i.e., design engineers), experts of subjective listening tests, and scientists in acoustics. No earthmoving machine operators were included. The noise stimuli were presented to the subjects in a quiet environment through high-quality electrostatic headphones with a flat response in the 40-40,000 Hz frequency range after being modified to account for the transfer function of the headphones used for playing back. Each listening session started with a learning phase, during which the experimenter provided the instructions needed to understand the correct procedure for the test. The subjects had to choose, within the pair, the stimulus they considered more annoying. The rating was given by each subject after listening to each pair of sound stimuli as many times as necessary in order to increase the concentration and reduce the probability of inconsistent responses. According to a procedure defined in Kendall and Babington Smith [20], the consistency for each subject and the agreement among the subjects were evaluated in order to guarantee the control of \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Parameter** & & **A** & **B** & **C** & **D** & **E** & **F** \\ \hline \multirow{2}{*}{Peak (dB)} & Left & 106.0 & 103.0 & 100.0 & 105.0 & 101.0 & 106.0 \\  & Right & 107.0 & 104.0 & 98.2 & 106.0 & 101.0 & 107.0 \\ \hline \multirow{2}{*}{\(L\) (dB)} & Left & 96.7 & 91.4 & 88.0 & 94.3 & 91.0 & 101.0 \\  & Right & 97.5 & 92.9 & 87.2 & 94.5 & 90.7 & 101.0 \\ \hline \multirow{2}{*}{\(L_{A}\) (dB(A))} & Left & 89.1 & 84.9 & 76.2 & 86.3 & 78.3 & 79.9 \\  & Right & 89.9 & 88.4 & 74.6 & 87.1 & 79.8 & 79.7 \\ \hline \multirow{2}{*}{\(N\) (some)} & Left & 88.4 & 68.6 & 40.4 & 75.6 & 46.0 & 55.5 \\  & Right & 92.9 & 78.2 & 37.2 & 78.8 & 47.7 & 55.7 \\ \hline \multirow{2}{*}{\(N_{50}\) (some)} & Left & 88.8 & 68.9 & 40.6 & 76.0 & 45.9 & 56.0 \\  & Right & 93.4 & 78.6 & 37.3 & 79.2 & 47.8 & 56.0 \\ \hline \multirow{2}{*}{\(S\) (acum)} & Left & 1.36 & 1.43 & 1.04 & 1.40 & 1.02 & 1.01 \\  & Right & 1.38 & 1.43 & 1.12 & 1.42 & 1.04 & 1.07 \\ \hline \multirow{2}{*}{\(S_{5}\) (acum)} & Left & 1.42 & 1.51 & 1.10 & 1.48 & 1.08 & 1.07 \\  & Right & 1.45 & 1.51 & 1.18 & 1.50 & 1.09 & 1.12 \\ \hline \multirow{2}{*}{\(R\) (asper)} & Left & 1.63 & 1.34 & 1.78 & 1.40 & 1.53 & 1.55 \\  & Right & 1.40 & 1.59 & 1.49 & 1.43 & 1.26 & 1.63 \\ \hline \multirow{2}{*}{_Fl.St._ (vacil)} & Left & 0.30 & 0.32 & 0.29 & 0.29 & 0.31 & 0.32 \\  & Right & 0.31 & 0.27 & 0.29 & 0.28 & 0.27 & 0.30 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Acoustic and psychoacoustic parameters for the six sound stimuli. the variance due to the emotional state of the judging individuals [25]. Three subjects (2 males and 1 female <29 years) did not satisfy these consistency tests, and their ratings were not used in the data analysis. The subjective responses were then arranged in matrices whose overall value is shown in Table 4.  
The number reported in each cell represents how many times the sound indicated on the left hand side of the row was judged more annoying than that heading the correspondent column. The subjective annoyance score (SAS) of the sound stimuli is shown in the last three columns in terms of (1) the overall value for each sound stimulus, with respect to all the others (Sum); (2) the ranking of the subjective scores (Rank); (3) the percentage value (%) normalized to the maximum score (160) that each stimulus could have obtained.