Evolution of the "ü" spoken in Soule from the diphthong "eu". The "u" of the diphthong does not continue the same process as the vowel "u". Furthermore, the northwestern Basques do not follow the same process as the vowel "u" and the "u" of the diphthong to "ü", while the Bearnaos never go from the "u" in "eu" to "ü"