The paper investigates the reasons for LTAS sensitivity to language change. Six bilingual Catalan/Castilian Spanish have produced 5 utterances of 8 corpuses with controlled phonetic content. Experiment 1 shows that the LTAS interlanguage effect does not vary when the interlanguage corpus similarity increases. Experiment 2 shows that corpuses with invariant between- or within languages dissimilarities exhibit variable LTAS dissimilarities, i. e. more LTAS dissimilarity in interlanguage comparisons. It is therefore concluded that the corpus content variations due to the languages own characteristics are no cause of the LTAS interlanguage variability.