When the process of retrieval for symbols fails, we may find that words are now unrecognizable to us--APHASIA
If I have lost the ability to understand spoken, written or signed words, it is called receptive aphasia.
In this case, I have an additional problem in that I don't understand my own speech as well. The lack of feedback will cause my speech to steadily deteriorate into jargon.
Ironically, I may not be aware of these deficits and hence, see no need for speech rehabilitation.
In expressive aphasia we may wish to speak, but we can't remember the words, and/or the grammar/ and/or their pronunciation.
It can be a total inability, but more often it is a partial loss (dysphasia).
In a situation like this moreover, verbage stored in the right hemisphere may rush to fill the void.
NOTES: Hear an exmple of Receptive Aphasia and obtain some more information on Aphasia
NOTES: Hear an example of Expressive Aphasia and obtain some more information on Apahsia