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5.13: Sometimes -s is [z], Sometimes [s]

Difficulty Level: At Grade Created by: CK-12
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1. Each of the following verbs ends with the suffix -s. Say each one carefully:

\begin{align*}& \text{gives} && \text{keeps} && \text{talks} && \text{grows} && \text{waits} && \text{strikes} \\ & \text{holds} && \text{says} && \text{resounds} && \text{sniffs} && \text{digests} && \text{unearths} \\ & \text{elects} && \text{unlocks} && \text{coughs} && \text{weighs} && \text{fastens} && \text{seems} \end{align*}

2. Sort the verbs into these two groups:

Verbs with -s pronounced . . .
[s] [z]
elects sniffs gives grows
keeps waits holds weighs
unlocks digests says fastens
talks strikes resounds seems
coughs unearths

3. Analyze each of the verbs in which -s is pronounced [s] into its free stem and suffix:

Verbs with -s pronounced [s] = Free Stem + Suffix
elects = elect + s
keeps = keep + s
unlocks = unlock + s
talks = talk + s
coughs = cough + s
sniffs = sniff + s
waits = wait + s
digests = digest + s
strikes = strike + s
unearths = unearth + s

Each of the free stems above should end with the sounds [p], [t], [f], [th], or [k].

4. When the suffix -s is added to a verb that ends in [p], [t], [f], [th], or [k], the -s is pronounced [s]. Everywhere else the suffix -s is pronounced [z].

Watch the Middles!

fast en s
fast en s
fast en s
fast en s
di gest s
di gest s
di gest s
di gest s
e lect s
e lect s
e lect s
e lect s
re sounc s
re sound s
re sound s
re sound s

Teaching Notes.

Item 4. Students may wonder about the seemingly arbitrary list of sounds after which -s is pronounced [s]. That list is due to our tendency to avoid putting voiced and unvoiced sounds together. The following table may be useful in making the list seem less arbitrary without necessarily immersing students in the technicalities of voicing.

Of course, if it seems appropriate, you could explain the difference between unvoiced and voiced sounds. The sounds in the left column are the unvoiced consonants in English. The sounds in the right column are their voiced partners. (For more on these unvoiced-voiced pairs and restraints on combining them, see AES, pp. 73-76.)

But if you choose not to get into the technicalities of voicing, you can simply make two points to the students about the sounds in the table: The first point is that sounds on the same row constitute a pair that are pronounced almost exactly the same (the difference being voicing). You can demonstrate this similarity of pronunciation by asking the students to pronounce the members of each pair or the sample words (for example, “[p], [b], [p], [b] . . .” or [pat], [bat], [pat], [bat] . . .“). Point out to them that with each pair, they hold their mouths the same way when they say the sound or word in the left column as they do when they say its partner in the right column. You may or may not add that there is a buzzing sound when they pronounce the sounds in the right column, that buzzing being the vocal cords vibrating when voiced sounds are pronounced..

The second point to make about the table is that we can put the sounds in the left column together ([ps] and [ts], as in cops and cats, for instance). And we can put sounds from the right column together ([bz] and [gz], as in cobs and dogs). But we cannot put sounds from the left column together with sounds from the right column (no [pz] or [tz] or [bs] or [gs].

All of the sounds after which the suffix -s is pronounced [s] are, like [s], in the left column. Whenever -s follows any of the sounds in the right column, it is pronounced [z], which is also in the right column.

The only other unvoiced sound in English is [h]. It is not in the table because it does not have a voiced partner and it does not ever come at the end of stems, so it never affects the pronunciation of -s. All other sounds are voiced: [m], [n], [ŋ], [l], [r], [w], [y] – and all vowels. Thus, we say that when -s follows any of the unvoiced sounds in the left column (other than [s], which is always followed by -es not -s), it is pronounced [s], and everywhere else it is pronounced [z] because everywhere else the -s suffix follows a voiced sound.

Left Column Right Column
[p] pat [b] bat
[t] tot [d] dot
[f] fine [v] vine
[s] sip [z] zip
[k] cod [g] god
[th] thin [th] then
[ch] chin [j] gin
[sh] dasher [zh] azure

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Date Created:
Feb 23, 2012
Last Modified:
Jul 07, 2015
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