Spectral moments vs discrete cosine transformation coefficients: Evaluation of acoustic measures distinguishing two merging German fricatives.

The results of the quantification of the acoustic differences between German /ç/ and /ʃ/ in three speaker groups with varying contrast realizations are presented. Data for two speaker groups were collected in Berlin and Kiel, where the contrast is still realized. Data for a third group were collected in Berlin from speakers of Hood German-a youth-style multiethnolect spoken by adolescents in multilingual and multicultural neighborhoods of Berlin-where the contrast has weakened or is even lost. A forced choice perception test showed that listeners reliably differentiate these two fricatives in minimal pairs produced by the speakers from Berlin and Kiel, but fail to do so for the productions of the Hood German speakers. The acoustic analysis reveals that spectrally, the fricatives are very similar in all varieties. The spectral moments (Center of Gravity, standard deviation, kurtosis, skewness) fail to reveal the differences between the fricatives that are apparent from visual inspection of the spectra and the perceived auditory differences. Analyses of the discrete cosine transformation coefficients, however, better quantify these differences. This study suggests that minute differences between fricatives that vary between speaker groups may be captured more reliably with discrete cosine transformations compared to spectral moments.