An extract from the book: Word Power by the author of this article.
The English language indicates that the action of the verb is in the past by having some form of the "d" or "t" sound end the word. We say some kind of "d" or "t" sound although the word is almost always written with a "d".
Many people who learn English are so confused by the irregular forms of the verbs that they give up and invent their own ways of referring to the past. Some say: "Yesterday I walk to work" or other ways to avoid using the past tense that they have never learned.
Sure, there are irregular words in English. The past of teach is taught; the past of buy is bought; the past of think is thought. But even these irregular words end in some kind of a "t" sound to indicate that the verb refers to the past. Luckily, there aren't too many of these irregular verbs. You just have to learn them. The good thing is that they behave more or less the same way.
But let's look at the regular verbs. Most English verbs are regular. To indicate the past, they put some kind of a sound made with the tongue touching the back of the upper teeth. Almost always it is the sound of a "d" or of a "t".
The ending of the verb “love” in the past: “I loved the movie” is very different from the ending of the verb “walk”: "I walked to work.” When it sounds like the letter “d”, it is a voiced sound, that is the vocal cords vibrate. When it sounds like a “t”, it is a voiceless or an unvoiced sound.
But how do you know when it should end with a voiced "d" sound and when with a voiceless "t" sound? Although you may not believe it, there is a "rule" that will help you to form the past of most English verbs. You may still make some mistakes but little by little you will feel the mistakes and will correct them. The structure of your mouth will force you to make the right sound.
The "rule" for the formation of the past is similar to the "rule" for the "s" at the end of plural nouns and verbs in the third person singlular of the present tense.
The rule of the "d" in three parts:
There is a one simple "rule" that covers the pronunciation of the "d" and "t" sounds.
The sound that indicates the past of the verb is the voiceless "t" sound when the verb ends in a voiceless consonant. On the other hand, the indication of the past is the voiced "d" sound when the verb ends in a voiced consonant.
The three parts of the rule are:
1. the voiceless "t" sound,
2. the voiced "d" sound,
3. the added syllable.
1. The voiceless (unvoiced) "t":
The "rule" tells us when the last sound of a verb is is like that of the words talk, cap, mess, etc (that is, a voiceless sound), the past of the verb ends with a voiceless (or unvoiced) sound like that of the word walked. The past of these verbs is talked, capped, messed and the "d" is unvoiced.
For example the letter "d" that represents the past in the written word is pronounced like the "t" of Tom (a voiceless sound) when the verb ends in a voiceless sound. So when the verb ends in voiceless sounds such as the letters k in the word looked, p in the word stopped, f in the word cuffed (or gh in the word laughed) the past is indicated by the voiceless "t" sound. This always happens so don't be fooled by the written letter "d".
The past tense of the verb is also indicated by a voiceless sound when the verb ends in any "hissing" sound such as the words: face, wash, crunch. All these sounds are voiceless so the verbs that end with them will always have the "d" of their past form sounded voicelessly and therefore become the forms faced, washed, crunched.
It is important to note that although the voiceless "d" is written "ed", you do NOT add a syllable to the original word.
2. The voiced "d":
The "d" is voiced in two situations:
a. when the word ends in a vowel sound such as, played, teed, owed, cued.
The "strange" vowels are also followed by a voiced "d" such as in the words: furred, papered, pawed. The past of verbs ending in a diphthong sound also end in a voiced "d" sound, for example in the words: plowed, paid, toyed .
b. when the word ends in a voiced consonant.
Some examples of the second case are: b as in the word robbed, n in the word drowned, l in the word mailed, g in the word logged, v in the word heaved, m n the word farmed, n as in the word panned, thesoundof the letters ng as in the word ring, r as in the word cars, v as in the word stoves, and thin the word bathed.
Remember that that the voiced "d" sound forms the past of verbs that end in a voiced consonant, for example, burned is the past of the verb burn and lovedis the past of love.
It is important to note that although the voiced "d" in these words is written with "ed", you do NOT add an extra syllable.
3. The added syllable
In both cases, when the verb ends in either the sound of the voiced "d" or the sound of the voiceless "t", the English language adds a syllable to the verb.
For example, the verbs in the present tense visit, vote, side, need, plant, adopt, add "ed" to make the past tense and become visited, voted, sided, needed, planted, adopted.
The "ed" is pronounced with a special vowel followed by a voiced "d". The special vowel is the "short i" which has the IPA symbol of the small capital “i”. We treat this sound in the book in the chapter on the short vowels. Remember a ship is not a sheep. You have to be able to hear the difference to be able to use this vowel in the added syllable.
It is only in this special case that you pronounce the second syllable of the past of a verb. Not all verbs have two syllables in the past. It is important that you realize that most common English verbs have only one syllable. Do not think that you have to pronounce the "ed" of the words such as walked, talked, played, tuned, tooled. Do not read these words as they were written in your language.
Although many verbs have "ed" in their past, it is just a strange note of English spelling. You often only pronounce one syllable with the past indicated by a voiced "d" or an unvoiced "t" according to which sound preceded the ending.
You only pronounce the "ed" when the root form of the verb ends with your tongue touching the back of your teeth, either with a voiced "d" sound or with an unvoiced "t" sound. For example, "Today, I heat the coffee but yesterday I heated it" (2 syllables because the last consonant is a "t"). But, "Today I talk to my friend but yesterday I talked on the phone." (one syllable because the last consonant is not a "t" or a "d")
The extra syllable: Listen to this as often as necessary for you to be able to distinguish the unvoiced "t" from the voiced "d".
Review and practice all parts of the “RULE”!
The first part of the "rule": the voiceless "t";
The second part of the "rule": the voiced "d" :
The third part of the "rule": the added syllable
