How do you pronounce "is there" in fast speech?

I'm not a native speaker of English, and I was recently puzzled with the question, "How can Americans put their tongue in z (is) position and then change to th (there) in such short time?"

May you explain to me how it is possible?

Solution 1:

Actually, it's not the /th/ that usually gets dropped. It's the /i/. First, in contractions:

What's there?
It's there.

And secondly, at the beginning of a sentence the /i/ is often dropped, so that the sentence actually starts on a /z/ sound:

zthere any coffee left? [Is there any coffee left?]

The /z/ sound is very brief and after experimenting with this for a while, it sometimes sounds like /sz/ (szthere). You start with the tongue almost stopping the breath at the front of the palate (the place where you would start a /t/ or /th/ sound, let some air through which begins a sibilance, add voicing which turns it into a /z/ for a few milliseconds, then slide the tongue up behind the teeth very rapidly to form the vocalized /th/.

In cases where the first syllable is not dropped, you do the process mentioned above except starting with a full vocalized vowel /i/, then moving the tongue to create the /z/ and so on. It's not hard for native speakers.

Solution 2:

Most of the time when speaking quickly, I drop the 'th' sound: "Izzair a doctor in the house?" Or, "There isn't any coffee left, izzair?" This is common in the Southern U.S. where I live. I also hear it pronounced "issair" as well.

Solution 3:

In practice people often don't enunciate the "th" when saying "is there" in rapid speech.

Some people have greater oral dexterity than others, some people habitually take more care to enunciate clearly, and most people enunciate more clearly in certain situations. But there's no special "technique" enabling Americans (or any other English speakers) to say things which OP might find difficult. People simply find it easier to produce the phoneme set of their mother tongue because that's what they hear and use most.

Solution 4:

In the "American Accent Training" book (Ann Cook, Barron's, ISBN 0.7641-1429-8) there is a section dedicated to the reduced sounds, which are "all those extra sounds created by the absence of lip, tongue, jaw, and throat movement."

As example of reduced sounds, the book reports some sentences, including the following ones (the pronunciation is not reported using the IPA characters):

It's the best. [ts th' best]
What's the matter? [w'ts th' madder]
What's the problem? [w'tsə präbl'm]
Who's the boss around here? [hooza bäss sərond hir]

In the first sentence, the i in it's is a reduced sound, but so is the e in the. In the third sentence, the "what's the" part is reduced to w'tsə. (The ə has the same meaning it has in the IPA alphabet.) In the fourth sentence, the "who's the" part is reduced to hooza.