I am not aware of any studies comparing the number of words an average person could expect to hear spoken in a typical day 500 years ago vs. the number that can be heard now, but the increase surely is vast.
( ( ( ( ( I ( ( am not ) ( aware ( of ( ( any studies ) ( comparing ( ( the number ) ( of ( words ( ( an ( average person ) ) ( could ( expect ( to ( hear ( spoken ( in ( ( a ( typical day ) ) ( ( ( 500 years ) ago ) ( vs. ( ( the number ) ( that ( can ( be ( heard now ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) , ) but ) ( ( the increase ) ( surely ( is vast ) ) ) ) . )
(ROOT (S (S (NP (PRP I)) (VP (VBP am) (RB not) (ADJP (JJ aware) (PP (IN of) (NP (NP (DT any) (NNS studies)) (VP (VBG comparing) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS words)) (SBAR (S (NP (DT an) (JJ average) (NN person)) (VP (MD could) (VP (VB expect) (S (VP (TO to) (VP (VB hear) (VP (VBN spoken) (PP (IN in) (NP (NP (DT a) (JJ typical) (NN day)) (PP (ADVP (NP (CD 500) (NNS years)) (RB ago)) (IN vs.) (NP (NP (DT the) (NN number)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (VP (VB be) (VP (VBN heard) (ADVP (RB now)))))))))))))))))))))))))))) (, ,) (CC but) (S (NP (DT the) (NN increase)) (ADVP (RB surely)) (VP (VBZ is) (ADJP (JJ vast)))) (. .)))
Though I've never read any research regarding how many words people heard back then compared to now, I'm sure the number has gone up.
( ( Though ( I ( ( 've never ) ( read ( ( any research ) ( regarding ( ( ( how many ) words ) ( people ( ( ( heard back ) then ) ( compared ( to now ) ) ) ) ) ) ) ) ) ) ) ( , ( I ( ( 'm ( sure ( ( the number ) ( has ( gone up ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Though) (S (NP (PRP I)) (VP (VBP 've) (ADVP (RB never)) (VP (VBN read) (NP (NP (DT any) (NN research)) (PP (VBG regarding) (SBAR (WHNP (WHADJP (WRB how) (JJ many)) (NNS words)) (S (NP (NNS people)) (VP (VBD heard) (ADVP (RB back)) (ADVP (RB then)) (PP (VBN compared) (PP (TO to) (NP (RB now))))))))))))) (, ,) (NP (PRP I)) (VP (VBP 'm) (ADJP (JJ sure) (SBAR (S (NP (DT the) (NN number)) (VP (VBZ has) (VP (VBN gone) (PRT (RP up)))))))) (. .)))