The symbol
v' may be said to represent a diaphone comprising both bi-labial and labio-dental voiced fricatives...The bi-labial sound...is commoner, amongst older speakers in particular.
...
The sound represented by
v in intervocalic position...may be described as a voiced bi-labial fricative, with non-palatal quality.
...
...
f' may be described as a breathed bi-labial fricative, with palatal quality.
...
The symbol
f represents a breathed bi-labial fricative...
— "The Irish of Ring, Co. Waterford"
http://www.celt.dias.ie/publications/cat/e/e2-3.html ____________________________
v'
This is a palatalized voiced bilabial fricative...
v
This is a velarized voiced bilabial fricative...
f'
This is a palatalized voiceless bilabial fricative...
f
This is a velarized voiceless bilabial fricative...
— "The Irish of West Muskerry, Co. Cork"
http://www.celt.dias.ie/publications/cat/e/e2-1.html ____________________________
v'
v' represents a voiced palatalised spread-lipped labio-dental fricative. It represents the same sound made with bilabial frication when it occurs before
u: or
u. Both bilabial and labio-dental friction are used before
o:...
Certain speakers retain the nasal quality in
v' (
mh)...
Some speakers, such as [Bríd Bean Uí Fhíne (B.F.),
c. 80, An Lochán Beag] have bilabial articulation of
v' in all positions.
w
w represents a voiced velarised lip-rounded fricative.
The friction is normally bilabial when it occurs (i) finally, (ii) after a velarised consonant, (iii) between vowels, where the friction is slightly weaker, (iv) before
L and
r followed by
u:,
u,
or
o:...
The friction is usually labio-dental when
w occurs (i) before
L,
r, followed by vowels other than
u:,
u, or
o:, (ii) preceded by
α: or
a:...
Certain speakers retain the nasal quality in
w (
mh)...
Certain speakers, such as B.F. use a bilabial
w in all positions.
Labio-dental articulation of w and f
It is difficult to give definite rules for the occurrence of the labio-dental and bilabial members of the
f and
w phonemes in the speech of those who have both articulations. Usage varies from speaker to speaker, within limits, and sometimes varies in the speech of one person. In the case of [Mícheál Ging (M.G.), 38, An Teach Mór] it may be of importance to note that he has a large, though not prominent, set of teeth and that the lips are normally slightly apart when 'at rest' although the teeth may be touching. The use of a velarised labio-dental fricative would seem to be, in part at least, due to a reluctance to make the full movement of the lips necessary to cause bilabial friction.
1 A slight movement of the upper lip in the direction of the lower one is noticed when he is making a velarised labio-dental, although the friction is visibly the result of the closeness of the lower lip to the upper teeth. The narrowing is made between the teeth and the inside portion of the lower lip, which is somewhat protruded, as is normal in lip-rounding. This labio-dental velarised
w is not at all similar to an English
v-sound, as it is both velarised and lip-rounded. The acoustic difference between it and the bilabial member of the phoneme is slight. The same remarks apply to the labio-dental velarised
f, as regards its articulation, its differing from an English
f, its closeness acoustically to the bilabial member of the phoneme.
f
f represents a voiceless velarised fricative, accompanied by slight lip-rounding. The friction is usually bilabial when it occurs (i) initially before
u:,
u,
o:,
o,
i:,
i, and
au, (ii) preceded by
u:...
The friction is usually labio-dental when it occurs (i) before
L, or
r, (ii) before
a:, or
α:, (iii) between vowels except when preceded by
u:...
Both labio-dental and bilabial friction are common in certain positions such as (i) before
o, (ii) preceded by
i: and followed by another vowel...
Certain speakers, for example B.F., use a bilabial
f in all positions.
f'
f' represents a sound which is made in the same way as
v', except that it is voiceless. It is made with bilabial friction under the same circumstances as
v'...
Certain speakers, for example B.F. use a bilabial fricative in all positions.
1 I have noticed M.G. making
b and
m with labio-dental contact on a few occasions. Some few speakers frequently use labio-dental plosives in place of bilabials, as a result of lazy articulation.
— "The Irish of Cois Fhairrge, Co. Galway"
