Elision means not pronouncing the consonants [t] & [d] in connected speech, when speaking naturally in everyday conversation.
[t] & [d] are elided when the next word begins with a consonant other than [h].
He arrived last Monday
Notice that it only happens with [t] & [d] when they are before another consonant, not when they are the last sound. When [t] & [d] are at the end of the sentence, they are normally pronounced fully because there is no need to connect the speech.
He arrived last night
Elision happens because it makes pronunciation easier. Try to pronounce last night as [ˈla:st ˈnait] and you will notice how hard it is.
Let’s see some more examples →
|next Tuesday||blunt man|
|nɛks ˈtjuzˌdeɪ||blʌn mən|
|cold wine||find this|
|koʊl waɪn||faɪn ðɪs|
Elision of [t] & [d] can also happen within a word.
Keep in mind that elision doesn’t happen before vowel sounds or when the word with final [t] or [d] is the last word of the sentence.
He arrived last autumn
The elision of [t] is especially important for negative contractions, which also accept elision even before vowels or [h].
Be aware that the final [d] or [t] sound in the regular past forms is usually elided by native speakers but you shouldn’t do it until you master pronunciation because it would sound as a present form, changing the meaning or making the sentence wrong.
If we are strict, [t] is only elided after voiceless consonants and [d] before voiced ones. However, we can start getting used to elision without paying attention to this as it is more important to get to know this pronunciation phenomenon than the rules themselves.