ASSIMILATION (T) before P

ASSIMILATION (T)before  P

It's a white piece of paper.

In fluent speech, if one word ends in a /t/ sound and the next word begins in a /p/ sound, the /t/ is pronounced slightly differently. In fact, we pronounce it as if it were almost a /p/ sound. So 'white piece of paper' becomes 'whi(te) piece of paper'.
This is an example of how sounds change in everyday speech - and it's called assimilation. Here are some more examples:

Examples
There are lots of grea(t) parks in London.
I love spli(t) pea soup.
I ha(te) potatoes.
My ma(te) picked us up from the airport.

split personality

sweet potato

test paper

private practice

secret police