[1]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945821/ Among
   hearing people, the phonological loop is partially relied upon
   for working memory but not exclusively. There's a heuristic - a
   "rule of thumb" that's used as a baseline, of 7 distinct items
   in working memory, +/- two, but according to this study, people
   born deaf do not have diminished working memory capacity,
   although they DO have fewer "items" available to recall in a
   serial fashion - at least *seem-to*. IN this article the
   rule-of-thumb itself is questioned because the 7 +/-2 was rather
   over-reaching... and in fact people who have hearing, their
   levels of serial item recall is typically at the same levels as
   ASL users with only minor adjustments to lab study. So, point
   is: The "extra two" that are sometimes measured are _likely_
   echoing in the phonological loop. Meaning: There's not much
   significance to the phonological loop to working memory.

References

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