OK, "house" /haʊs/, but "houses" /ˈhaʊzɪz/ Source
Why does "s" changes to "z"? I thought it should be /ˈhaʊsɪz/.
OK, "house" /haʊs/, but "houses" /ˈhaʊzɪz/ Source
Why does "s" changes to "z"? I thought it should be /ˈhaʊsɪz/.
The /z/ in /ˈhaʊzɪz/ was caused by voicing assimilation, which historically applied in a fairly automatic way to fricative sounds in English. The sound [z] is the voiced counterpart of [s], and in Old English, an /s/ in the middle of a word was pronounced as voiced [z] when it came between vowels—which are voiced sounds. (There were some complications related to prefixed and compound words.)
We can see the effect of the Old English rule of voicing assimilation for fricative consonants in some other words where a final voiceless fricative in the singular changes to a voiced fricative in the plural. A few examples: leaf-leaves, wolf-wolves, and for some speakers path-paths, truth-truths. (From an etymological perspective, the final consonant of leaf was actually "originally" voiced in Proto-Germanic, but devoiced in Old English because it was in word-final position. But the resulting distribution of voiced and voiceless forms is the same as for words like house and path whose fricatives come from Proto-Germanic voiceless sounds.)
But as Peter Shor noted in a comment, this process is not automatic in modern English, and in fact the general pattern now is that voiceless fricatives between vowels do not assimilate in voicing; they stay unvoiced (as in the words blouses and spouses, for speakers who pronounce the singular forms of these words with voiceless /s/).
So the plural form of house has become irregular in pronunciation.
Here's a related question: Pronunciation: ‘lousy’ vs. ‘mousy’. Why?
This is strange. I grew up in Boston+NY and have always said "houZes". I first noticed people pronouncing it 'houSes" several years ago on TV (I now live in Europe). Since then I keep hearing it in this unvoiced form! I thought it was a California thing, or maybe a generational shift.
And now the other day when I was watching Silicon Valley I thought they were using the unvoiced S in surprising places for example saying "pleaSe" rather than "pleaZe".
I wonder if the S vs. Z sounds less assertive and is being used to sound less confrontational in these "woke" times, like perhaps people are forming statements as questions with rising intonations ("uptalk") but that is pure speculation. Have to keep an eye on thiS....
I say blouses and spouses with a /z/, but that's because the singular also is pronounced /z/ in many varieties of English. I pronounce house with an /s/ and houses with a /z/, and of course the verb form "to house" I pronounce with a /z/.
I've heard both used, with /ˈhaʊsɪz/ usually in a more formal context or when speaking more slowly. I imagine /ˈhaʊzɪz/ is just assimilation of the voicing when the speaker isn't thinking about it, like the /j/ in "don't you" assimilating toward the /t/ and becoming /ʃ/ in casual conversation ("donchoo").