When learning to cue English, beginners can easily be influenced by spelling. Instructors sometimes include lessons on trickier aspects on applying cues to the the pronunciation of words. Usually, time is designated to practice distinguishing /sssssssss/ and /zzzzzzzzz/. Another tricky aspect can be the various ways "-ed" endings are pronounced and cued.
Phonemes generally are either voiced or voiceless. The /ttttttttt/ in bat is voiceless, and the /ddddddddd/ in bad is voiced.
So, what’s the pattern?
1) If the root word ends in /ttttttttt/ or /ddddddddd/, the [-ed] ending is pronounced (cued) //ɪd, ed, or əd//.
Examples: waited knitted voted
/wae, tid/ /ni, tid/ /voe, tid/
Folded worded needed
/foe, l, did/ /wur, did/ /nee, did/
2) If the root word ends in a voiced sound other than /ddddddddd/, the [-ed] ending is pronounced (cued) /d/.
Examples: bored paged called learned
/boe, r, d/ /pae, j, d/ /kaw, l, d/ /ler, n, d/
3) If the root ends in a voiceless sound other than /t/, the ending is pronounced (cued) /t/.
Examples: worked watched fished sipped
/wer, k, t/ /wah, ch, t/ /fi, sh, t/ /si, p, t/