Occasionally a new sound is introduced, but it is likely to melt away before long.  In Chaucer’s day the old Anglo-Saxon ue (written y) had long become unrounded to i, but a new set of ue-vowels had come in from the French (in such words as due, value, nature).  The new ue did not long hold its own; it became diphthongized to iu and was amalgamated with the native iw of words like new and slew.  Eventually this diphthong appears as yu, with change of stress—­dew (from Anglo-Saxon deaw) like due (Chaucerian due).  Facts like these show how stubbornly a language resists radical tampering with its phonetic pattern.

Nevertheless, we know that languages do influence each other in phonetic respects, and that quite aside from the taking over of foreign sounds with borrowed words.  One of the most curious facts that linguistics has to note is the occurrence of striking phonetic parallels in totally unrelated or very remotely related languages of a restricted geographical area.  These parallels become especially impressive when they are seen contrastively from a wide phonetic perspective.  Here are a few examples.  The Germanic languages as a whole have not developed nasalized vowels.  Certain Upper German (Suabian) dialects, however, have now nasalized vowels in lieu of the older vowel + nasal consonant (n).  Is it only accidental that these dialects are spoken in proximity to French, which makes abundant use of nasalized vowels?  Again, there are certain general phonetic features that mark off Dutch and Flemish in contrast, say, to North German and Scandinavian dialects.  One of these is the presence of unaspirated voiceless stops (p, t, k), which have a precise, metallic quality reminiscent of the corresponding French sounds, but which contrast with the stronger, aspirated stops of English, North German, and Danish.  Even if we assume that the unaspirated stops are more archaic, that they are the unmodified descendants of the old Germanic consonants, is it not perhaps a significant historical fact that the Dutch dialects, neighbors of French, were inhibited from modifying these consonants in accordance with what seems to have been a general Germanic phonetic drift?  Even more striking than these instances is the peculiar resemblance, in certain special phonetic respects, of Russian and other Slavic languages to the unrelated Ural-Altaic languages[168] of the Volga region.  The peculiar, dull vowel, for instance, known in Russian as “yeri"[169] has Ural-Altaic analogues, but is entirely wanting in Germanic, Greek, Armenian, and Indo-Iranian, the nearest Indo-European congeners of Slavic.  We may at least suspect that the Slavic vowel is not historically unconnected with its Ural-Altaic parallels.  One of the most puzzling cases of phonetic parallelism is afforded by a large number of American Indian languages spoken west of the Rockies.