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The pronunciation of any word in English (or any language at all) is not Universal.  This is because there are many different dialects of The English Language — both throughout America, and also world-wide.  The pronunciations that are presented on GiveMeSomeEnglish!!! are based-upon a combination of both “common usage”, and the most neutral accent used in The International Common Tongue — a.k.a. “American English”.
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Helpfulness – For this word:  the “H” is pronounced audibly;  the “e” is short;  the “p” is (often) stopped;  for the “-ful” suffix – the “u” is pronounced as an true-schwa (this is the standard pronunciation of this suffix in The Common Tongue);  and for the “-ness” suffix – the “e” is pronounced as an i-schwa;  and the “ss” combination is pronounced simply like the single letter “s” (this is the standard pronunciation of this letter combination in The Common Tongue) & (this is the standard pronunciation of this suffix in The Common Tongue).

– /HEHL[P]-fəl-nihs/ – /ˈhɛl[p].fəl.nə(ɪ)s/ – Notice also that the stress is on the first syllable –

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Learn More About The Word “Helpfulness” On Wiktionary

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