# Open-Plan Offices: Comparison of Methods for Measuring Psychoacoustic Intelligibility Parameters
## 3 Results
### Acoustic Analysis of Intelligibility
#### 3.2.2 Subjective Analysis  
The subjective methods were based on the subjective assessment of intelligibility based on the Statistical Acoustic Theory. For the subjective analysis, the consonant loss parameter was used to evaluate intelligibility by means of a quality scale. The scale uses the Puetz formula for _%ALCons_ modified by [PERSON], expressing intelligibility between 0-1. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Factors**} & \multicolumn{5}{c}{_STI_} \\ \hline
**Point** & _SPL Zone_ & **Type of Sound** & **Condition** & **Type of Effect** & \(\beta\)** **Coefficient** & _p-Value_ & **Mean** & **Stand Desv** \\ \hline  & & ON & & S & 0.079 & \(<\)0.001 & 0.71 & 0.144 \\  & & ON & Out area & I & \(-\)0.050 & \(<\)0.001 & 0.67 & 0.133 \\  & & ON & Both area & I & 0.048 & \(<\)0.001 & 0.76 & 0.147 \\
3 & Stable & ON & Out area & I & \(-\)0.128 & 0.044 & 0.61 & 0.085 \\
5 & Changes & & S & 0.069 & 0.029 & 0.77 & 0.157 \\
8 & Changes & ON & & I & \(-\)0.067 & 0.034 & 0.66 & 0.152 \\  & Changes & ON & Out area & I & 0.153 & 0.001 & 0.76 & 0.161 \\
10 & Changes & ON & Out area & I & \(-\)0.109 & 0.015 & 0.53 & 0.074 \\
12 & Stable & & & S & \(-\)0.092 & 0.004 & 0.59 & 0.16 \\
13 & Stable & & & S & \(-\)0.089 & 0.005 & 0.59 & 0.181 \\
16 & Stable & ON & & I & \(-\)0.064 & 0.044 & 0.7 & 0.167 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Relationship between _STI_ and study factors, \(\alpha=0.05\) (ON = Office Noise record, S = Simple effect, I = Interaction). Figure 5: Points with significative changes in _STI_. This diagram shows the points and sound sources with significant changes in the average values during the study. These percentages generate a classification for subjective evaluation, with categories of excellent, good, fair, and poor [14]. The subjective methods were also analyzed using the Dirac(r) software, with which the estimated %_ALCons_ results were obtained. This parameter had a special treatment since the %_ALCons_ values obtained had to be adjusted to a Lognormal distribution to perform the GLM analysis. For this adjustment, a Box-Cox transformation (\(\lambda\) = 0) was used [28]. The subjective rating was analyzed using the Dirac(r) program, which yielded the %_ALCons_ values to be subsequently classified according to the subjective categorization of speech quality (Table 1). The %_ALCons_ parameter presented the influence of some factors in the variation of its average percentages. The factors of interest that influenced the %_ALCons_ were the assignment, the location of the measurement points (\(p\) = 0.006, f = 0.33), and the type of sound (\(p\) < 0.001, f = 0.57). In addition, the interaction between some factors presented some changes in this parameter. For example, a medium effect was found for the influence of sound nesting on sound condition (\(p\) < 0.001, f = 0.30) and the interaction of this with measurement point assignment (\(p\) = 0.04, f = 0.40). Sound nesting explains that the variation in sound emission has an influence depending on the type of sound transmitted and how it interacts at each point where the acoustic parameters are measured. In this study, the general average was %_ALCons_ = 6.51, which can be classified as adequate quality for the intelligibility of this enclosure. Some specific points presented some changes, such as the case of Point 5 with a large effect that had a %_ALCons_ = 3.71 \(\pm\) 1.59 (\(p\) = 0.024, d = 1); Point 10 had a large effect with %_ALCons_ = 7.96 \(\pm\) 2.82 (\(p\) = 0.039, d = 0.73); Item 12 had a large effect with %_ALCons_ = 9.78 \(\pm\) 2.12 (\(p\) = 0.003, d = 1); and Item 13 had a large effect with %_ALCons_ = 10.21 \(\pm\) 2.47 (\(p\) = 0.007, d = 1) (Figure 6). In addition, some factors stood out in the effect on the loss of consonants, particularly with the sound conditions. For example, the type of sound with office noise presented a large effect on the average %_ALCons_ = 1.84 \(\pm\) 0.52 (\(p\) < 0.001, d = 1).