The Pronunciation of Irish (Gaelic) Consonants

GRMA as an spreagadh, a Phatchy!

In Irish, each consonant generally has 4 different phonemes, i.e. a different sound that changes the meaning;

broad strong B - bó 'cow'
broad weak B - (a) bhó 'his cow'
slender strong B - beo 'alive'
slender weak B - bheo 'alive' (lenited/softened)

Consonants can be categorised according to which mouth-parts ('articulators') are used in pronouncing them. In Irish, consonants (except glottal [h]) are Labial (lips) or Lingual (tongue);

LABIAL consonants;
All Irish labial consonants are bilabial (both lips, no teeth!) unlike English f and v which are labiodental (lower lip to upper teeth).
Bilabial (lower lip to upper lip); p ph, b bh, m mh.

Slender bilabial consonants are pronounced with the lips pulled back and spread against the teeth (making the mouth 'slender'), making a higher-pitched sound than its nearest English equivalent.
Broad bilabial consonants are pronounced with the lips pushed forward and kept wide apart from the teeth (making the mouth 'broad'), making a lower-pitched sound than its nearest English equivalent.

LINGUAL consonants;
lingual consonants are either coronal (tongue's crown/front) or dorsal (tongue's back).

Slender lingual consonants are palatal(ised), i.e. the consonant is pronounced with the middle of the tongue raised forwards towards the hard/front palate, like English sound y [ j ], generally producing a higher-pitched sound than its nearest English equivalent.
Broad lingual consonants are velar(ised), i.e. the consonant is pronounced with the back of the tongue raised backwards towards the soft/back palate, like English sound w [w], generally producing a lower-pitched sound than its nearest English equivalent.

At least in theory*, the dorsal consonants are broad-vs-slender strong-vs-weak c g ng and the coronal consonants are broad-vs-slender strong-vs-weak s t d n r l.
*Some consonants that were originally lingual have come to be pronounced in a different part of the vocal tract (throat/mouth/nose), e.g. th (originally a tongue-tip alveolar voiceless continuant, in my scholarly opinion!) has lost its tongue-contact and become [h] which is a (glottal) voiceless continuant.

- the dorsal/tongue-back consonants are c g ng, with broad-or-slender & strong-or-weak variants, though ng is always strong; 4 Cs + 4 Gs + 2 NGs = 10 dorsal phonemes.
- the coronal/tongue-front consonants are s t d n l r, with broad-or-slender & strong-or-weak variants) - All consonants before the word's first vowel are by default strong. A weak=soft consonant is nowadays shown by putting an un-etymological h after the softened consonant except after the coronal sonorants n l r; Single n l r are by default strong when before the word's first vowel, i.e. word-initially ná lá rá(dh). After the word's first vowel, strong n l r are generally written double (banna balla barra) whereas weak n l r are written single (mana mala mara).

A phoneme is a "meaningful sound" that can change a word's meaning if replaced, e.g. English nest lest rest.

In theory, English has one n phoneme, one l phoneme, and one r phoneme, each with a different sound, but the Japanese language -for example- considers the English sounds [l] and [ɹ] as allophones of only one sound (unbelievable, no?), and most native Japanese-speakers learning English cannot initially hear or pronounce the difference between English's phonemes /l/ and /ɹ/ in the way native English speakers do.
Through effective teaching and/or the strong self-determination to eventually acquire the praised prestigious pronunciation of native English-speakers, practically every native Japanese-speaker who acquires fluent (=flowing, fast) English acquires the ability to pronounce these phonemes as pronounced by native English-speakers of any particular dialect.

In theory, Irish has 4 n phonemes, 4 l phonemes, and 4 r phonemes, each with a different sound, but English-speakers -for example- consider the Irish sounds [nˠ nʲ n̪ˠ ɲ] [lˠ lʲ l̪ˠ ʎ] [ɾˠ ɾʲ rˠ (rʲ)] as allophones of only three respective sounds [n l ɹ] (unbelievable, no?), and most English-speaking learners of Irish cannot initially hear or pronounce the difference between Irish's phonemes /nˠ nʲ n̪ˠ ɲ/, /lˠ lʲ l̪ˠ ʎ/, and /ɾˠ ɾʲ rˠ (rʲ)/ in the way native Irish speakers do.
Through ineffective teaching and/or the strong self-determination to never acquire the ridiculed unprestigious pronunciation of native Irish-speakers, practically no native English-speaker who acquires fluent (=flowing, fast) Irish acquires the ability to pronounce these phonemes as pronounced by native Irish-speakers of any particular dialect.

Do you see what I did there...?

(The situation of Irish n l r is complicated by dialectal variation. For example, modern Kerry Irish has lost the strong/weak distinction in coronal sonorants (n l r) so the original 12 coronal sonorant phonemes of Old Irish/Goidelic have been reduced in Kerry to only 6, namely broad/slender n l r (2x3=6, maith thú).