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)))) (. .)))
According to the research I've seen, the average person hundreds of years ago heard many more words over the course of the day compared to a modern human being.
( ( According ( to ( ( the research ) ( I ( 've seen ) ) ) ) ) ( , ( ( ( the ( average ( person hundreds ) ) ) ( of years ) ) ( ago ( ( ( ( heard ( many ( more words ) ) ) ( over ( ( the course ) ( of ( the day ) ) ) ) ) ( compared ( to ( a ( modern ( human being ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (PP (VBG According) (PP (TO to) (NP (NP (DT the) (NN research)) (SBAR (S (NP (PRP I)) (VP (VBP 've) (VP (VBN seen)))))))) (, ,) (NP (NP (DT the) (JJ average) (NN person) (NNS hundreds)) (PP (IN of) (NP (NNS years)))) (ADVP (IN ago)) (VP (VBD heard) (NP (JJ many) (JJR more) (NNS words)) (PP (IN over) (NP (NP (DT the) (NN course)) (PP (IN of) (NP (DT the) (NN day))))) (PP (VBN compared) (PP (TO to) (NP (DT a) (JJ modern) (JJ human) (NN being))))) (. .)))