From Longman Dictionary of Contemporary Englishunheardun‧heard /ˌʌnˈhɜːd $ -ɜːrd/ adjective LISTEN#not heard or listened to Her cries for help went unheard.
Examples from the Corpus
unheard• Sadly, our voice went unheard at the time.• The proposals went largely unheard because we remained on a semi-war footing throughout the Cold War.went unheard• Sadly, our voice went unheard at the time.• But it went unheard by the intensely hostile and suspicious Orthodox hier archy. 