# More on Sibilant Devoicing in Spanish Diachrony: An Initial Phonetic Approach
## 3 The Perception Experiment
### Results
Duration also determines the participants' election depending on the phonological category (F(7, 5740) = 8.281, \(p<0.0001\)): when duration increases, the proportion of voiced classifications significantly decreases in all fricative sibilants and in the dentoalveolar affricates.16 Once again, palatal affricates do not show this behaviour, though the results are not statistically relevant: when parsed as voiceless, their duration is shorter than when recognized as voiced. Footnote 15: [[https://www.cds.org/](https://www.cds.org/)]([https://www.cds.org/](https://www.cds.org/))  
More interestingly, there is a correlation of fraction of unvoiced frames and duration depending on the sibilant type (F(8, 5740) = 6.601, \(p<0.0001\)). In [z] (b0 = \(-0.001\), se = 0.0001, t = \(-2.562\), p \(<0.010\)), [s] (b0 = \(-0.002\), se = 0.0001, t = \(-5.199\), \(p<0.0001\)) and [d\(\overline{3}\)] (b0 = \(-0.002\), se = 0.001, t = \(-2.577\), \(p<0.010\)), longer duration and higher proportion of unvoiced frames imply less voiced parsing; on the other hand, [more cases than expected labelled as voiced when fraction of unvoiced frames and duration increase (b\({}_{0}\) = 0.003, se = 0.001, t = 2.476, \(p<0.013\)), though correct parsings still outweigh incorrect answers. Overall, the participants' judgements confirm the acoustic measurements regarding duration and fraction of unvoiced frames, thus showing that they are reliable parameters to establish voicing degree, which seem to be acoustically and perceptually related. Figure 4: Box plots representing duration values (blue boxes) and fraction of unvoiced frames (orange boxes) in stimuli labelled as voiced and voiceless in each phonological category. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Stimuli**} & \multicolumn{3}{c}{**Fraction of Unvoiced Frames (\%)**} & \multicolumn{2}{c}{**Consonant Duration (ms.)**} \\ \cline{3-6}  & & \(\bar{\vec{x}}\) & **sd** & \(\bar{\vec{x}}\) & **sd** \\ \hline \multirow{2}{*}{[s]} & voiced & 70.35 & 9.62 & 95.45 & 13.97 \\  & voiceless & 80.25 & 11.58 & 108.48 & 9.34 \\ \hline \multirow{2}{*}{[z]} & voiced & 31.51 & 26.37 & 65.64 & 18.26 \\  & voiceless & 40.36 & 30.10 & 70.74 & 20.40 \\ \hline \multirow{2}{*}{[J]} & voiced & 50.37 & 17.65 & 95.87 & 11.43 \\  & voiceless & 66.26 & 17.60 & 112.82 & 14.87 \\ \hline \multirow{2}{*}{[s]} & voiced & 25.60 & 20.07 & 95.43 & 24.13 \\  & voiceless & 43.57 & 20.82 & 100.15 & 19.22 \\ \hline \multirow{2}{*}{[fS]} & voiced & 46.19 & 27.79 & 135.20 & 28.25 \\  & voiceless & 71.16 & 24.56 & 172.04 & 45.62 \\ \hline \multirow{2}{*}{[d\(\bar{2}\)]} & voiced & 33.67 & 21.38 & 128.77 & 24.27 \\  & voiceless & 45.31 & 20.44 & 140.79 & 20.41 \\ \hline \multirow{2}{*}{[\(\bar{\vec{t}}\)]} & voiced & 51.92 & 13.19 & 146.18 & 16.84 \\  & voiceless & 65.75 & 13.20 & 149.61 & 28.30 \\ \hline \multirow{2}{*}{[d\(\bar{\vec{s}}\)]} & voiced & 31.42 & 21.38 & 132.89 & 11.68 \\  & voiceless & 29.03 & 19.17 & 111.78 & 20.52 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Mean value of fraction of unvoiced frames (in percentages) and duration (in milliseconds) in the stimuli labelled as voiced or voiceless for every category. Standard deviation values are also provided.