The prototype of the graphic form of the Armenian letter Ն is the Greek “nu” – not the classical N, but one of its varieties. But it is not possible to determine, which variant exactly was used by Mashtots, because there were numerous variations of Ն in the IV–V centuries.
Letter Յ denotes the sound [y]. At first, its phonetic meaning was confined to this, but with the lapse of time it changed. Apparently, no later than the XIII century, letter Յ got to be pronounced as [h] at the beginning of words.