**5.** *How* **is it evaluated?**

points, except for the point measured in the alley. In particular, D50 was above 65% for high frequencies and under 50% for mid and low frequencies. Therefore, we restate that this square works better for speech and has too much definition for music. Perhaps for this reason, and because of its size, the square is ideal for solo singers or those accompanied with chamber instruments. Finally, Carrer de Santa Llúcia (bottom right) has an inherent tendency to lower definition when we move away from the source or we are behind it. Particularly, points 1 and 2 are more suitable for speech or opera, whilst points 3, 4 and 5 have better features for music.

**Figure 7.** Definition (D50) of the different environments: Sant Felip Neri (top left), Plaça del Rei (top right), Plaça Sant Iu

In Plaça de Sant Felip Neri (top left from **Figure 8**) we can see that EDT values for 500 Hz and 1 kHz are similar to Ts values, except for the Ts peak at point 5, which is the result of a measurement error due to the high amount of background noise at that time. Similarly, in Plaza del Rei (top right), Sant Felip Neri (bottom left) and Carrer Santa Llúcia (bottom right), the EDT levels are very similar to the Ts levels, which indicates that there is a good sound

Again, we can note that the audience zone belongs to points 1 and 2.

*4.2.5. Early decay time (EDT)*

(bottom left), and Carrer Santa Llúcia (bottom right).

54 From Natural to Artificial Intelligence - Algorithms and Applications

diffusion in these environments.

Quantitative approaches are the main methods of scientific research. They focus on analysing the degree of association between quantified variables, promulgated by logical positivism. Therefore, possible answers need to be constrained in order to evaluate results objectively [43]. Some evaluation investigations have already been done with architecture students [44, 45].

Qualitative research is less common in education areas, because it focuses on detecting and processing intentions. Unlike quantitative methods, qualitative approaches require deduction to interpret the results. The qualitative approach is subjective, because it is assumed that reality is multifaceted and cannot be reduced to a universal parameter. Interviewers are passive observers, they take notes and classify them [46]. These methods have traditionally been related with social sciences, due to their association with human factors and the user's experience. In fact, *User Experience*, UX, is a discipline focused on the study of behavioral patterns in working environments. Our case study is framed in teaching process usability [47]. Thus, a brief discussion of what usability means is mandatory.
