Nasal raising can happen when 'a' or 'ai' is in contact with a nasal letter ('n' or 'm'), causing the 'a' (as in 'ah') to change to an 'e' sound, as in 'eh'.  In some cases, an intermediate sound, shown as 'æ' is found.

The maps show, however, that the effect is not always found and that the distribution patterns vary.

With 'Màiri' (Mary) and 'màthair' (mother), the raising is mainly in the south - western part of the Gaelic area, extending northwards along the west coast mainland to Wester Ross.  The intermediate 'æ' is found, as might be expected, near the limits of the two main types.

With 'cnàimh' (bone), however, the vowel change is found mainly in the north of the area, especially in Skye and in the Outer Hebrides, with a smaller area in the south-west taking in Islay, Arran and parts of Kintyre.  With, 'cnàimh' it is also more difficult to discern a pattern for the intermediate 'æ' pronunciation.  In common with other Gaelic words starting with 'cn' e.g. 'cnoc' (hill)' the 'n' is pronounced throughout the area as 'r', but nasal raising still occurs - this does not happen with 'crann' (tree) where the 'c' is followed by 'r'.