/pf/ occurs only in loanwords from Standard German. Just as among many native German-speakers, it tends to be simplified to [f] word-initially. For example, Pflicht ('obligation') is pronounced [fliɕt], or in careful speech [pfliɕt].
/v/ is realized as [w] when it occurs after /k, ts, ʃ/, e.g. zwee[tsweː] ('two').
/p, t, k/ are voiceless fortis [p, t, k]. They are aspirated[pʰ, tʰ, kʰ] in most positions, but not when /s/ or /ʃ/ precedes in the same syllable, or when another plosive or affricate follows.
/j/ is frequently realized as [ʒ], e.g. Juni[ˈjuːniː] or [ˈʒuːniː] ('June').
The normal realization of /ʀ/ is more often a trill[ʀ] than a fricative [ʁ]. The fricative variant is used after short vowels before consonants. If the consonant is voiceless, the fricative is also voiceless, i.e. [χ]. Older speakers use the consonantal variant [ʀ ~ ʁ] also in the word-final position, where younger speakers tend to vocalize the /ʀ/ to a central vowel [ə] or [ɐ].
/χ, ʁ/ have two types of allophones: alveolo-palatal[ɕ, ʑ] and uvular [χ, ʁ]. The latter occur after back vowels, whereas the former occur in all other positions.
The [ʑ] allophone appears only in a few words intervocalically, e.g. Spigel[ˈʃpiʑəl] ('mirror'), héijen[ˈhəɪ̯ʑən] (inflected form of héich 'high'). Note that an increasing number of speakers do not distinguish between the alveolo-palatal allophones [ɕ, ʑ] and the postalveolar phonemes /ʃ, ʒ/.
In external sandhi, syllable-final /n/ is deleted unless followed by [n t d ts h], with few exceptions. Furthermore, some unusual consonant clusters may arise post-lexically after cliticisation of the definite articled' (for feminine, neuter and plural forms), e.g. d'Land[dlɑnt] ('the country') or d'Kräiz[tkʀæːɪ̯ts] ('the cross'). Due to cluster simplification this article often disappears entirely between consonants.
Phonetically, word-final /b, d, dʒ, ɡ, v, z, ʒ, ʁ/ are realized exactly the same as /p, t, tʃ, k, f, s, ʃ, χ/. In most cases, they are realized the same as the main allophones of /p, t, tʃ, k, f, s, ʃ, χ/ (i.e. voiceless), but when the next word begins with a vowel and is pronounced without a pause, they are realized the same as the main allophones of /b, d, dʒ, ɡ, v, z, ʒ, ʁ/, i.e. voiced and are resyllabified, that is, moved to the onset of the first syllable of the next word (the same happens with /ts/, which becomes [dz], and the non-native affricate /pf/, which is also voiced to [bv]). For instance, sech eens (phonemically /zeχ ˈeːns/) is pronounced [zəˈʑeːns], although this article transcribes it [zəʑ‿ˈeːns] so that it corresponds more closely to the spelling. Similarly, eng interessant Iddi[eŋ intʀæˈsɑnd‿ˈidi] ('an interesting idea').
Pronunciation of the letter g
In Luxembourgish, the letter g has no fewer than nine possible pronunciations, depending both on the origin of a word and the phonetic environment. Natively, it is pronounced [ɡ] initially and [ʁ ~ ʑ] elsewhere, the latter being devoiced to [χ ~ ɕ] at the end of a morpheme. Words from French, English and (in a few cases) German have introduced [ɡ] (devoiced [k]) in other environments, and French orthography's "soft g" indicates [ʒ] (devoiced [ʃ]).
By the now very common mergers of [ʒ] and [ʑ], as well as [ʃ] and [ɕ], this number may be reduced to seven, however. The pronunciation [j] is also (generally) not obligatory but a common alternative to [ʑ] in the environment indicated below.
The nasal vowels appear only in loanwords from French, whereas the oral front rounded vowels appear in loans from both French and German.
The opposition between close-mid and open-mid vowels does not exist in native Luxembourgish words. In non-native words, there is a marginal contrast between the close-mid /øː/ and the open-mid /œː/.
/i, iː, u, uː, o/ are close to the corresponding cardinal vowels [i, u, o].
Some speakers may realize /o/ as open-mid [ɔ], especially before /ʀ/.
/e/ has two allophones:
Before velars: close-mid [e], which for some speakers may be open-mid [ɛ] – this is especially frequent before /ʀ/.
All other positions: mid central vowel with variable rounding, but more often slightly rounded [ə̹] than unrounded [ə̜]. Contrary to Standard German, the sequence of [ə] and a sonorant never results in a syllabic sonorant; however, Standard German spoken in Luxembourg often also lacks syllabic sonorants, so that e.g. tragen is pronounced [ˈtʀaːɡən], rather than [ˈtʀaːɡn̩] or [ˈtʀaːɡŋ̍].
/eː, oː/ are higher than close-mid [e̝ː, o̝ː] and may be even as high as /i, u/.
The quality of /æ/ matches the prototypical IPA value of the ⟨æ⟩ symbol ([æ]).
/ɐ/ appears only in unstressed syllables. Phonetically it is a near-open near-back unrounded vowel [ɐ̠]. It is similar to /ɑ/, though it is shorter and somewhat more central. Phonemically, it can be analyzed either as a marginal phoneme or a non-prevocalic sequence of /e/ and /ʀ/.
The ending points of the closing diphthongs tend to be fairly close, more like [i, u] than [ɪ, ʊ].
The starting points of /əɪ̯, əʊ̯/ are typically schwa-like [ə], but the first element of /əɪ̯/ may be more of a centralized front vowel [ë̞].
The starting points of /æːɪ̯, æːʊ̯/, /ɑɪ̯, ɑʊ̯/ as well as /iə̯/ and /uə̯/ are similar to the corresponding short monophthongs [æ, ɑ, i, u].
The first elements of /æːɪ̯, æːʊ̯/ may be phonetically short [æ] in fast speech or in unstressed syllables.
The centering diphthongs end in the mid central unrounded area [ə].
/oɪ̯/ appears only in loanwords from Standard German.
The /æːɪ̯ – ɑɪ̯/ and /æːʊ̯ – ɑʊ̯/ contrasts arose from a former lexical tone contrast: the shorter /ɑɪ̯, ɑʊ̯/ were used in words with Accent 1, whereas the lengthened /æːɪ̯, æːʊ̯/ were used in words with Accent 2 (see Pitch-accent language#Franconian dialects.)
Additional phonetic diphthongs arise after vocalisation of /ʀ/. These are [iːə̯, uːə̯, oːə̯, ɛːə̯], with [iːɐ̯, uːɐ̯, oːɐ̯, ɛːɐ̯] as possible alternatives. However, the sequence /aːʀ/ is realized the same as long /aː/, unless a vowel follows within the same word.
In loanwords from Standard German (such as Bad Dürkheim and Föhr) [yːə̯] and [øːə̯] also occur, again with [yːɐ̯] and [øːɐ̯] as possible alternatives.