## 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  
Since the one-third octave frequency bands are those closest to the critical bands of the human ear [38], an analysis was carried out of the relations between the subjective variables associated with the effects of noise and the equivalent sound levels for each of the one-third octave frequency bands. The aim was to study the capacity of the frequency bands to explain the occurrence and importance of the effects considered here. It is necessary to point out that all of the subjective variables related to the effects of noise on pedestrians were significantly correlated with Leq in each of the one-third octave bands with a significance level of at least \(p\leq 0.05\), and many of these correlations had values of \(p\leq 0.01\) or \(p\leq 0.001\). The intensity of these significant correlations can be seen in Figure 4. If the values of the correlation coefficients between variables (a), (b), (c), (h), and (i) with the equivalent unweighted noise levels for each of the one-third octave frequency bands are analysed (Figure 4a), it can be seen that the correlation coefficient for irritability (a) reaches maximum values of around 0.7 in the low-frequency bands between 100 and 160 Hz and in the mid-high frequencies (800-2000 Hz). In this regard, it is worth noting that one of the one-third octave band sections with higher values of the correlation coefficient coincide with the bands where the road traffic noise level reaches the highest values [55]. In the case of startle (b), annoyance in the ears (c), and a noisy street (i), high correlation values were observed with the sound level recorded in the one-third octave frequency band of 25 Hz, with r values of 0.70, 0.67, and 0.75, respectively. In addition, the variable of a noisy street (h) also reached values of approximately 0.75 at 50 Hz and 5 kHz. As is shown in Tables 3 and 6, the subjective variable of perceived annoyance (i) had the highest correlation coefficient, with values of approximately 0.78 for the one-third octave bands between 200 Hz and 16 kHz and a maximum value of 0.82 at 100 Hz. From the results of the correlation coefficients between variables (d), (e), (f), and (g) (related to interference within conversations) and the equivalent unweighted noise level for each of the one-third octave frequency bands (Figure 4b), it seems that mid-frequency and low-frequency bands above 50 Hz play a similar role in interruptions to in-person (d) and telephone (f) conversations. However, different results were found when analysing the response to raising the volume of conversations. Low-frequency bands show high relevance in the case of conversations with someone nearby (e), with values for the correlation coefficient of up to 0.77 around the 25 Hz band, whereas mid-high frequency bands are more important in terms of raising the volume in telephone conversations (g), with a maximum r value of 0.68 in the 500 Hz band. This detailed analysis of the one-third octave frequency bands again indicates a possible effect of the noise level measured in the different parts of the audible sound spectrum on the need to raise the voice in conversations, depending on whether they are conducted in the street or by telephone. In addition, it is of interest to carry out an objective analysis of the possible relation between the structures of the correlation coefficients obtained for the noise spectrum in the one-third octave bands for the different noise effects under study. The aim in this case is to look for similarities in the structure, rather than similarities in the absolute intensity of the explanations.