The Merriam-Websters dictionary shared an article they wrote about how <laser> is an acronym. This is something I never knew. Laser stands for “light amplification by stimulated emission of radiation”. The gist of the article was that use of the <s> was related to the word it represented and not its pronunciation. The thing is is that <s> is sometimes, or often, pronounced as /z/.

As a native English speaker, we often don’t really even realize when we pronounce words with a /z/ that is spelled with a <s>. We just do. It often occurs finally in small words like: is, has, was, his.  With these next groups of word it is also final but the spelling includes a final <e>: because, bruise, cruise, house, lose, tease, phase, choose, cause. The <e> is an indicator that these words are not plurals. Also note all of these words have a vowel phoneme before the [z]. There are a few cases where the [s] is retained, such as lease, mouse, promise, which is a story for another time.

Some may have learned about this pronunciation when learning about suffixing. When an <s> is added either for pluralization or first person singular verbs, the pronunciation occurs after voiced consonants and vowels. Examples include: dogs, beds, moves, words. Another situation occurs when needing to add an <s> where the final phone is a sibilant, often described as “hissing” pronunciations. In these cases, natural English speakers know that another pulse of speech is added and voicing occurs to make it a [z].  In spelling, an <-es> suffix is added. Examples include: misses, watches, dishes, fizzes, dodges. All of these have the <-es> suffix and the <s> is pronounced [z]. 

A less known pattern that can be studied is when an <s> is intervocalic, or between two vowels, such as music, season. The <s> is pronounced as [z]. Additional examples to contemplate include: cousin, disease, easy, design, husband. I also think this word is interesting in pronunciation: <business>.

With all that said, going back to <laser>, the <s> would be pronounced [z] because it is intervocalic. Acronyms are interesting in how they are pronounced, but this one evolved in our language as we would expect. And, if you find this interesting, I will leave you with the word <maser>.

References

Britannica, The Editors of Encyclopaedia. “Sibilant.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 21 Apr. 2016, www.britannica.com/topic/sibilant.

“Laser Acronym Explanation.” Merriam-Webster, Merriam-Webster, www.merriam-webster.com/words-at-play/laser-acronym-light-amplification.

Smith, Rachel. “How to Pronounce the Letter S.” Rachel’s English, 20 May 2015, rachelsenglish.com/pronounce-letter-s/.

Smith, Rachel. “Letter S Pronounced [z]” Rachel’s English, 20 May 2015, rachelsenglish.com/pronounce-letter-s/.