Here are some links if you want to know more about the subject:

Assimilation in spanish

Assimilation test

Assimilations of the /j/

Phonetics and phonology blog

Another example in english:

Another example in spanish:

"Un perro"
"Un beso"

This phenomenon also occurs in Spanish

When he said: "Por lo tanto" he pronounced "po lo tanto".

Here are some examples of assimilation:

"Goodnight"

Assimilation examples

Consonant assimilation

In the case the two phonemes can fuse completely and give a birth to a different one.
This is also called "Coalescence"


Example Do you smoke?: In slower speech we might say: dju sməʊk. In fast, casual speech we could say: dʒu sməʊk.

Reciprocal assimilation

When both sounds (the assimilating and the assimilated one) under go changes.

Historically this has occurred in words like:

Soldier, picture or fissure.

where the reconstructable earlier pronunciation /‘soυldjər/, /‘pıktu:r/, /‘fısju:r/ has become /‘səυldзə/,/‘pıkt∫ə/, /fı∫ə/

In current colloquial English, similar assimilation occurs in phrases such as "What d’you want" /wt∫əwnt/ or
Could you?  /‘kυdZu:/.

Regressive Assimilation

It happens when the following sound in a word influences the preceding sound.

Progressive assimilation

If the phoneme changes to match the preceding phoneme, it is progressive assimilation.


For example:


What’s the problem? In slower speech we might say: wɒts ðə ˈprɒbləm. In very fast, casual speech we could say: wɒtszəˈprɒbləm


Another example:

There are 4 types of assimilation:

Regressive, progressive, reciprocal and consonant assimilation.

Assimilation by L.F Brosnahan & Bertil Malmberg

The general term for adaptive modifications of a sound in the chain by neighbouring
-and not necessarily immediately neighbouring-sound is assimilation (...)


- "Introduction to Phonetics".

Assimilation by Ortiz Lira

The process by which sounds are influenced by neighbouring sounds and come to share some or all of their phonetics characteristics.

Assimilation by Peter Roach

In natural connected speech, sounds belonging to one word can produce changes in the sounds of neighboring words.