--- /RefinedSoundex.java	2023-07-05 02:32:36.398157948 +0200
+++ /Codec-1/src/java/org/apache/commons/codec/language/RefinedSoundex.java	2023-07-05 02:32:36.398157948 +0200
@@ -141,7 +141,7 @@
         if (!Character.isLetter(c)) {
             return 0;
         }
-        return this.soundexMapping[Character.toUpperCase(c) - 'A'];
+return this.soundexMapping[Character.isLetter ( c )  - 'A'];
     }
 
     /**
