\section{Background}
\label{sec:bg}

In this section, we provide a detailed background of two languages from our dataset - Scots (sco) and Nubi (kcn) - which form the basis of our linguistic error analysis later on. Through the representation of these two languages, we aim to highlight the difficulties in modeling speech from similar low-resource, typologically diverse languages.

\subsection{Scots}
Scots (ISO 639: sco) is a language native to the United Kingdom and the Republic of Ireland, with over 1,508,540 speakers and 2,444,659 reporting being able to speak, read, or write the language\footnote{\url{https://www.gov.scot/policies/languages/scots}}. It is a minority language in Europe and is considered vulnerable according to UNESCO; its Agglomerated Endangerment Status according to Glottolog is threatened \cite{550905, glottolog}. It belongs to the Indo-European language family and has roots in Old English. Similar to English, Scots follows the \texttt{SVO} (Subject-verb-object) word order. For example, ``\textit{I eat lettuce}'' becomes ``\textit{Ah eat lettuce}'' in Scots. There are 5 mainly recognized dialects: Central, Southern, Northern, Insular, and Ulster. Many scholars argue whether Scots is its own language or a dialect of English \citep{alma99153242810001452, trudgill1984language}. However, the Scottish government recognizes Scots as its own distinct language. Despite its over 1 million speakers worldwide, Scots is considered a low-resource language due to limited parallel corpora and gold standard annotations \citep{lameris-stymne-2021-whits}. Recently, Scots has been added to the Scottish curriculum in schools in an attempt to revitalize and maintain use of the language. 

Modeling Scots for speech-based LLMs is challenging due to its unique position on a linguistic continuum with Scottish Standard English (SSE). This often results in code-mixing, making it difficult for models to delineate language boundaries. Additionally, Scots features high regional variation in its sound system, and the vowel length is determined by the phonetic environment, a feature not present in standard English. In Scots, plural verbs take an -s suffix (e.g., ``the men is lachin'') unless the subject is an immediately adjacent pronoun \citep{modern_scots, history_scots, grammar_scots}. These factors, combined with the ``Scottish Cringe'' - a socio-cultural internalized feeling of linguistic inferiority that can lead to code-switching in formal recording environments — make it difficult to obtain truly representative data \citep{MoChridhe_2020}.

\subsection{Nubi}

Nubi (ISO 639: \texttt{kcn}) is an Arabic-based Creole language spoken by approximately 50,000 people, primarily in Uganda and Kenya \citep{nubi_stress_tone, nubi_genetic_owens, avram2020substrate}. It’s Agglomerated Endangerment Status according to Glottolog is shifting, and the Catalogue of Endangered Languages lists it as threatened \cite{glottolog, 569683}. It evolved in the late 19th century within military camps in Sudan and Upper Egypt, separating from its lexifier, Sudanic Arabic, around 1885 \citep{wellens2005nubi, plural_formation_nubi, morphologization_jonathan}. Approximately 90\% of its basic vocabulary is derived from Arabic \citep{origin_african_nubi}. Similar to English, Nubi has a balanced 5 vowel system and has two primary dialects: Ugandan (Bombo) and Kenyan Nubi \citep{owens2006creole}.

Modeling Nubi presents several unique challenges for speech LLMs. Phonologically, Nubi exhibits significant variation between lento (slow) and allegro (fast) speech. In allegro forms, vowels are frequently elided through processes of syncope (internal deletion) and apocope (final deletion), which often obscures the underlying CV syllable structure and complicates phonetic boundary detection for speech models \citep{wellens2003arabic, origin_african_nubi}. Furthermore, while Nubi has lost the pharyngealized and geminate consonants of its Arabic lexifier, it has ``imported'' phonemes such as \textipa{/p/}, \textipa{/v/}, and 
\textipa{/\textltailn/} from African substrate and adstrate languages like Swahili and Luganda.

Morphosyntactically, Nubi lacks grammatical gender and the complex person-number verbal inflections found in Arabic. Plural marking is optional and can be indicated through suffixation 
(e.g., \textit{-á}, \textit{-ín}) or stress shifts. This grammatical optionality and the use of suprasegmental features—where final stress and high pitch are used to distinguish passive from active verb forms—make Nubi particularly difficult to model accurately through audio alone \citep{wellens2003arabic}.

Syntactically, Nubi follows a strict Subject-Verb-Object (\texttt{SVO}) word order \citep{wellens2003arabic, amer2023relexification}. Minor category lexical items, such as the definite article (de) and cardinal numerals, are postnominal (following the noun), diverging from the prenominal structures typical of Arabic. These combined factors make it difficult to use multilingual LLMs for Nubi ASR.

% \small
% Nubi is a language native to Uganda and Kenya and has about 50,000 speakers worldwide. It is an Arabic-based Creole and uses the Arabic writing system. 80\% of Nubian vocabulary is derived from colloquial Arabic. As Nubi is a creole, it developed from a pidginized variety of Arabic, which originated in the 19th century in the camps of the Egyptian army in Upper Egypt and the Sudan \citep{wellens2003arabic}. Although the language is from Uganda, most speakers reside in Kenya, specifically, Nairobi. It is distinct and not to be confused with Nubian languages, which were born in Egypt. Similar to English, Nubi has a balanced 5 vowel system \citep{owens2006creole} and is mutually intelligible across the two dialects that exist: Bombo and Kenyan Nubi. It follows an \texttt{SOV} (Subject-object-verb) grammatical order, unlike its Arabic ancestor. 