## 3 Results and Discussion
### Acoustic Variables Associated with Maximum or Minimum Values of Sound Energy
#### 3.3.2 Analysis in One-Third Octave Frequency Bands
For this purpose, a correlation study was carried out between the values of the correlation coefficients for the different pairs of effects to be considered, such as those in Table 7. The dependent variable was taken as the one that appears in the rows; for example, the results for the Pearson correlation coefficient obtained for the one-third octave frequency bands for irritability (a) are capable of significantly explaining those obtained for the spectrum for the variable of interrupting a conversation with someone nearby (d), with a correlation coefficient of 0.56 and a significance level of \(p<0.001\). Several findings can be observed from Table 7. Firstly, it is noted that the frequency band structure that causes the effect of irritability (a) is like the one that causes the effect of interrupting a conversation, regardless of whether it is with someone nearby (d) or on the phone (f). This result, in addition to reinforcing the previous ones, is based on a detailed analysis of their spectra, and indicates a greater degree of similarity between the spectra that cause these three noise effects. In the same way, startle (b) is shown to be closely related to annoyance in the ears (c). Another noteworthy aspect from Table 7 is that the two effects of interrupting a conversation, (d) and (f), seem to have a common cause in terms of the spectrum structure, as well as the effects of having to raise the volume in a face-to-face conversation (e) or on the phone (g). Moreover, when the medium of communication is  
Figure 4: Correlation coefficients between subjective variables and the equivalent unweighted noise level for each of the 1/3 octave frequency bands: (**A**) variables (a), (b), (c), (h) and (i); (**B**) variables (d), (e), (f), and (g). the telephone, a similar spectral structure of the noise causes both to have to raise the volume (g) or to pause the conversation (f). Something similar takes place in face-to-face conversations, but with a weaker effect. For a perception of the street as noisy (h), the spectral structure of this effect appears to be closely related to that of annoyance in the ears (c) and is also somewhat related to having to raise the volume in a conversation with someone nearby (e). Finally, it is worth noting that annoyance (i) shows similarities in terms of the frequency spectrum with three of the four effects on conversation quality, i.e., (d), (f), and (g). It may be of interest to note that in some cases, significant linear relationships with a negative sign are obtained, indicating that, to some extent, the structures of the sound spectra that cause some effects are inverse to those that cause others. In this sense, it is important to note, for example, that with a significance value of \(p\leq 0.001\), the spectral structure related to perceived annoyance (i) is opposite to that related to annoyance in the ears (c), and to that related to startle (b), with \(p\leq 0.01\). The spectral structure related to perceiving the street as noisy (h) is the opposite of that related to interrupting a conversation on the phone (f) (\(p\leq 0.01\)) or to that related to the effect of irritability (a) (\(p\leq 0.05\)).