DEC - We are taught that ‘an’ precedes a word begins with vowels (e.g., a, e, i, o, u), whereas ‘a’ precedes a word begins with consonants (e.g., b, t, s). Why are there some exceptions, like ‘an MTR station’ and ‘a uniform’? Also, why are there two indefinite English articles (e.g., a, an)?

Question

Group 6 - question 2

Answer 1

1) Why are there some exceptions, like ‘an MTR station’ and ‘a uniform’?

The most significant feature that triggers choices of ‘a’ or ‘an’ is based on a following sound, not a following letter.  

Special Case: 

British English: a herb (H is pronounced - /hɜːb/) 

American English: an herb (H is silent - /ɜːrb/) 

Specifically, judgement of vowel sounds does not depend on literal letters ‘a, e, i, o, u’ but on their IPA representation. (English vowels: /iː, ʊ, uː, e, ə, ɜː, ɔː, æ, ʌ, ɑː, ɒ, ɪə, eə, əʊ, aʊ, eɪ, aɪ, ɔɪ, ʊə/)

1. MTR station – UK /em.tiː.ɑː steɪʃn/ US /em.tiː.ɑːr steɪʃn/ 
2. Uniform – UK /juːnɪfɔːm/ US /juːnɪfɔːrm/ 

Although the letter ‘M’ is not a member of ‘a, e, i, o, u’ literally, the initial sound is pronounced as /e/, a vowel sound. Thus, ‘MTR station’ is paired with ‘an’ instead of ‘a’. Same for ‘uniform’, though the first letter is ‘u’, the initial sound /j/ is not a vowel. Hence, it is preceded by ‘a’, not ‘an’. 

Comments

2) Why are there two indefinite English articles (e.g., a, an)?  

The phonetic environment determines the rule for choosing ‘a’ or ‘an’. Therefore, the reason for the existence of two indefinite articles in English is also related to phonetics and phonology. 

Another potential possibility attributes to the principle of economy, where speakers economise on avoiding challenging sound sequences by the article ‘an’. The existence of two consecutive vowels causes difficulty in pronunciation because it will promote glottalisation ([ʔ]: in ‘V_V’) in English (Garellek, 2012). The glottal stop is articulated by obstructing airflow in the glottis. A brief temporal gap with no air release occurs within contiguous vowels. Thus, it cannot be pronounced smoothly, like ‘uh-oh’ [ʌʔoʊ].  

Furthermore, connected speech is a noticeable phenomenon in English. It means that sounds are connected using identical or intermediate articulatory manner to save time and energy (Alameen & Levis, 2015). For instance, if the /p/ follows /n/, it will be pronounced as /m/ (e.g., green park [ɡriːn pɑːk → ɡriːm pɑːk]). However, glottalisation within adjoining vowels results in speech organs taking a new position and spending more energy on pronunciation, which violates the principle of economy.  

Accordingly, ‘a’ is a base form of the indefinite article. Inserting the /n/ sound between two vowels facilitates pronunciation (VCV), resulting in another article ‘an’. 

Phonological Rule: ∅ → [-n] / [ə]_#V 

References: 

Alameen, G., & Levis, J. M. (2015). Connected speech. The handbook of English pronunciation, 157-174.  

Garellek, M. (2012). Glottal stops before word-initial vowels in American English: distribution and acoustic characteristics. UCLA Working Papers in Phonetics, 110(1).