## 3 Results and Discussion
### Acoustic Variables Associated with Sound Energy over the Whole Audible Spectrum

Table 3: Correlation coefficients between subjective variables and acoustic variables associated with sound energy over the whole audible spectrum. indicator that was specifically developed to allow a good relationship with the perception of sound level, and this can be seen to be rather worse than L\({}_{\text{Zeq}}\) for the effects of startle (b); annoyance in the ears (c), and in particular (as it is closely related to the objective of this variable), a perception of the street as noisy (h). However, when the values of annoyance (i) were analysed, the results were more as expected. It should also be highlighted that, in general, none of the energy indicators studied here were very effective in explaining the appearance or variability of the effects related to face-to-face or telephone communication, although loudness and loudness level had the highest correlation coefficients in regard to interrupting a phone conversation (f) and raising the volume of their voice on a phone conversation (g), respectively. In this sense, it is worth noting that the difference found for the effect of raising the volume of their voice in a conversation with a nearby person (e) if we compare with the results with the rest of the effects related to verbal communication, (d), (f), and (g), for all the energy indicators except NR and NC. Moreover, for the remaining effects, NR and NC seemed to play a weaker role in explaining the variability of all the subjective variables apart from annoyance (i) and irritability (a). In view of these results, it may be useful to take into account indicators such as NR, NC, and NCB in noise characterisation studies in urban outdoor environments, regardless of whether they are generally used indoors. The outcome for the NCB indicator is of particular interest; it was better than or similar to the others, even when compared to the loudness and loudness level, which are rather more complex indices to obtain, since they take into account in greater detail the way in which humans perceive sounds. After describing the general aspects listed in Table 3, a detailed analysis was conducted of the implications of these results. Firstly, it is important to point out that the average energy of the sound wave over the full spectrum is a relevant sound characteristic for estimating the occurrence and importance of effects such as irritability (a), startle (b), raising the volume of the conversation in situ (e), the noisy street (h), and annoyance (i), with Pearson correlation coefficients of between 0.70 and 0.81. The highest values for the explanation of variability were obtained for annoyance, and this has a certain uniformity for all the acoustic variables analysed in this section. In relation to conversations, some differences were found between the variables of raising the volume of the conversation in situ (e) and on the phone (g). When a conversation is held in person, the average energy over the full spectrum is a relevant aspect, and the indicators that do not include weights for low frequencies, such as L\({}_{\text{Zeq}}\) or L\({}_{\text{Ceq}}\), seem to explain a higher proportion of the variability than those that do, such as L\({}_{\text{Aeq}}\). On the other hand, if a conversation is held on the phone, the average energy in the full spectrum is less useful, and the medium-high frequency seems to be more important in explaining the variability than the low frequency. When the results for in situ (d) and phone (f) conversation interruption are studied, the in-situ effect is explained to a greater extent. Since all of the acoustic variables have basically the same explanatory power for this effect of noise, this means that high, medium, or low frequencies all seem to have a similar impact.