## 2 Materials and Methods
In a review of these sound sources, in addition to the different sources associated with road traffic (related to the engine, exhaust, brakes, etc. ), the following types of sources and examples can be distinguished: \begin{table}
\begin{tabular}{c c c} \hline \hline
**Variables** & **Meaning** & **Value Range** \\ \hline \hline  & (a) & Irritability & 0–10 \\  & (b) & Startle & 0–10 \\  & (c) & Annoyance in the ears & 0–10 \\  & (d) & Interruption of a conversation with & 0–10 \\  & & someone nearby & \\  & (e) & Raising the volume of their voice to speak with & 0–10 \\  & (f) & Interruption of a phone conversation & 0–10 \\  & (g) & Raising the volume of their voice during a & 0–10 \\  & (h) & Noisiness of the street & 0–10 \\  & (i) & Annoyance & 0–10 \\ \hline  & \(L_{Zeq}\) & Unweighted equivalent sound level & 60–81 dB \\  & \(L_{Aeq}\) & A-weighted equivalent sound level & 48–73 dB \\  & \(L_{Ceq}\) & C-weighted equivalent sound level & 58–79 dB \\  & \(L_{Aleq}\) & A,I-weighted equivalent sound level & 52–75 dB \\  & \(L_{Cleq}\) & C,I-weighted equivalent sound level & 63–81 dB \\ Energy (full & _Loutness_ & Subjective judgement of the intensity of a sound & 7–30 sones \\  & _Loutness level_ & Loutness level = 10 \(\times\) log\({}_{2}\)(Loudness) + 40 & 68–89 phones \\ spectrum) & _NR_ & Highest noise ratio curve touched by the & 45–71 \\  & _NC_ & Highest noise criteria curve touched by the & 43–70 \\  & _NC_ & Highest balanced noise criteria curve touched by & 42–65 \\  & _NCB_ & the measured spectrum & \\ \hline  & \(L_{ASmx}\) & A,S-weighted maximum sound level & 68–87 dB \\ Acoustic & \(L_{AFmx}\) & A,F-weighted maximum sound level & 70–89 dB \\ objective & \(L_{A1 mx}\) & A,I-weighted maximum sound level & 70–91 dB \\ variables & \(L_{CSmx}\) & C,S-weighted maximum sound level & 77–96 dB \\  & \(L_{Crmax}\) & C,F-weighted maximum sound level & 80–99 dB \\ (measurements) & Energy & \(L_{Crmax}\) & C,I-weighted maximum sound level & 81–100 dB \\  & (maximum or & \(L_{Cpeak}\) & C-weighted peak sound level & 90–111 dB \\  & minimum) & \(L_{ASmin}\) & A,S-weighted minimum sound level & 35–55 dB \\  & \(L_{AFmin}\) & A,F-weighted minimum sound level & 33–54 dB \\  & \(L_{A1 min}\) & A,I-weighted minimum sound level & 35–55 dB \\  & \(L_{CSmin}\) & C,S-weighted minimum sound level & 48–65 dB \\  & \(L_{Crminit}\) & C,F-weighted minimum sound level & 46–62 dB \\  & \(L_{Crminit}\) & C,I-weighted minimum sound level & 49–66 dB \\ \hline  & \(L_{\alpha 20\text{-}200 Hz}\) & Equivalent sound level in the range 20–200 Hz & 59–81 dB \\  & _SIL3_ & Speech interference level (average \(L_{eq}\) of 1000, & 41–65 dB \\ Energy (parts of & & & \\  & audible & & 1000, 2000 and 4000 Hz octave bands) & 42–65 dB \\ spectrum) & _PSIL_ & Preferred speech interference level (average \(L_{eq}\) of & 43–68 dB \\  & \(L_{Ceq}-L_{Aeq}\) & Difference between \(L_{Cq}\) and \(L_{Aeq}\) & 1–4 dB \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Subjective and objective variables registered in the city of Cáceres, together with a brief description of their meaning and the range of values for each of them. * Sound events associated with traffic, but excluding sounds due to the engine and rolling noise: ambulance sirens, horn usage, loud music coming from inside the vehicle, car doors closing, traffic light sounds for visually impaired pedestrians, etc. These sounds were detected in 18.8% of the surveys conducted. * Sounds related to natural sound sources: birdsong without specifying the type, stork sounds, sounds generated by the wind, and sounds generated by water. These appeared in 35.2% of the surveys. * Sounds of human origin or from their pets: conversations, footsteps, children playing, a baby crying, a dog barking, footsteps, phone call sounds, etc. These appeared in 82.0% of the surveys. * Finally, sounds of work or machinery origin: unspecified construction noises, lawn-mowers, grinders, chainsaws, cranes, etc. These appeared in 9.4% of the surveys.