Aspiration, in this context, means the injection of a puff of air before or after a consonant.  It is not to be confused with lenition (sometimes also called aspiration), where the sound of some consonants is changed by various rules of Gaelic grammar and is shown in writing by insertion of letter 'h' e.g. his car = a chàr with the 'ch' pronounced as 'ch' in loch.

 

Aspiration is found in varying degrees in the Gaelic speaking world.  In the 'cat' example, the pre-aspiration of 't' varies widely. None is found in a crescent stretching from northern Sutherland, through Easter Ross and Perthshire, and on to Kintyre and Arran in the south.  Mild aspiration is found in west Lewis, north and west Sutherland and easter Ross, with strong aspiration in eastern Lewis, Harris, Skye and west mainland apart from Ardnamurchan, Appin and Morvern.  In these areas and in most area east of the Great Glen, the aspiration is in the form of 'ch' (as in loch) either lightly or strongly.

The Survey also shows that in Lewis and Harris, 'e' is used rather than 'a'.

 

The 'cù' maps illustrate two features;

1) the use of ü (pronounced as in French 'tu') is found particularly in Lewis, but also in wester Ross and in the Loch Alsh area (see CÙ2 map). The Survey shows that ü is a further back vowel  (i.e. closer to 'u' than 'i') on the mainland than it is in Lewis.

2) Aspiration seems to be mixed in Lewis, tending to be found more on the east side of the Island. On the mainland, Wester Ross does not use aspiration but it occurs in the  Loch Alsh area.

 

3) This area of aspiration continues south with 'u' pronunciation  in north west Argyll and into the Great Glen (see map CÙ1). There is an isolated small area of aspiration in extreme south east of Sutherland and eastern Easter Ross

 

4) In Kintyre and Aran, the Survey shows that the word for 'dog'  is 'madadh' rather than 'cù', in several cases, though in Arran, 'ma' is given as 'mwe' - this is found also in 'math' (good).