Final Sounds of “ed” and “s” Explained

Final “ed” Sounds and Final “s” Sounds

The final sounds of the “ed” ending of regular verbs in the past simple tense, differs depending on the final sound before the “ed” is added.

1.       Everyday I boil water. (present simple tense)

2.       Yesterday, I boiled water. (past simple tense with “ed” ending) – The final sound before the  “ed” was added is /l/, and after the /l/ sound, the “ed” has a /d/ sound.

3.       In the morning, my son usually kicks a ball. (present simple tense)

4.       Last week, my son kicked a ball every day. (past simple tense with “ed” ending) – The final   sound before the “ed” was added has a /k/ sound, the “ed” has a /t/ sound.

5.       I always wait until it is safe, before I cross the road. (present simple tense)

6.       Last Monday I waited for twenty minutes to cross the road. (simple past tense with “ed” ending) – The final sound before the “ed” was added has a /t/ sound, the “ed” adds an extra syllable with the /ɪd/ sound.

The three final sounds of the “ed” endings

1.       /d/
2.       /t/
3.       /ɪd/

Voiced Sounds vs Unvoiced Sounds

A simple explanation of voiced sounds and unvoiced sounds is as follows:

When the air needed to produce a sound requires air to pass over the vocal flaps (vocal chords), this causes a vibration in the throat (you can feel these vibrations by holding your hand on your throat), and this is referred to as a voiced sound.

When the air needed to produce a sound comes from the front of the mouth, instead of over the vocal flaps, this is referred to as an unvoiced sound. There is no vibration in the throat.
Let’s look again at the three sounds of the “ed” endings.

1.       /d/ – a voiced sound
2.       /t/ – an unvoiced sound
3.       /ɪd/ – a voiced sound

Here is the Rule Used

If the final sound before the “ed” is added is an unvoiced sound, we use the unvoiced “ed” sound, conversely, if the final sound before the “ed” is added is a voiced sound, we use the voiced sound.

Example:

“Boil” ends with a voiced /l/, so we use the voiced “ed” sound of /d/.

“Kick” ends with an unvoiced /k/ sound, so we use the unvoiced “ed” sound of /t/.

When a word ends with a /t/ or /d/ sound before the “ed” is added, we use the /ɪd/ sound.

The final “s’  sounds work in the same way, with /s/ as the unvoiced sound, and /z/ as the voiced sound.