documentclass{article}
usepackage[style=authoryear]{biblatex}

DeclareSourcemap{maps[datatype = bibtex]{map{
%% 1. Find year in brackets and sort them as if they were without brackets
    step[fieldsource = year,
        match = regexp{A[(.+)]z}, final]
    step[fieldset = sortyear, fieldvalue = {$1}]
%% 2. Abbreviate an entry such as Adam J[ohn] Smith to Smith, Adam J.
    step[fieldsource = author,
        match = regexp{[[^]]+]},
        replace = .]
%% 3. Change US postal codes such as 'MA' to 'StateMA'
    step[fieldsource = location,
        match = regexp{,s*(MA|CA|NY)},
        replace = regexp{,~\State{$1}}]
    }}}
% then change 'StateMA' etc. to AP style abbreviations 'Mass.' etc.
defState#1{csname State#1endcsname}
defStateMA{Mass.}
defStateCA{Calif.}
defStateNY{N.Y.}

begin{filecontents}{jobname.bib}
@ARTICLE{western1889,
    AUTHOR = "Aug[ust] Western",
    TITLE = "Kurze darstellung des norwegischen lautsystems",
    JOURNALTITLE = "Phonetische Studien",
    YEAR = "1889",
    PAGES = "259--282",
    VOLUME = "2"}
@BOOK{lehiste1970,
    AUTHOR = "Ilse Lehiste",
    TITLE = "Suprasegmentals",
    YEAR = "1970",
    LOCATION = "Cambridge, MA",
    PUBLISHER = "The M.I.T. Press"}
@BOOK{hoff1946,
    AUTHOR = "Ingeborg Hoff",
    TITLE = "Skjetvem{aa}let",
    YEAR = "1946",
    LOCATION = "Oslo",
    NUMBER = "1",
    PUBLISHER = "Jacob Dybwad",
    SERIES = "Skrifter utgitt av Det Norske Videnskaps-Akademi i Oslo. II. Historisk-filosofisk klasse. 1946"}
@INCOLLECTION{hoff1968,
    AUTHOR = "Ingeborg Hoff",
    BOOKTITLE = "Aurskog og Blaker",
    EDITOR = "[Eyvind Lillevold]",
    TITLE = "M{aa}let i Aurskog og Blaker",
    YEAR = "[1968]",
    LOCATION = "[Aurskog og Blaker]",
    PAGES = "685--752",
    PUBLISHER = "Bygdeboknemnda for Aurskog og Blaker",
    VOLUME = "3"}
end{filecontents}
addbibresource{jobname.bib}

begin{document}
nocite{*}
printbibliography
end{document}

documentclass{article}
usepackage[style=authoryear]{biblatex}

DeclareSourcemap{
  maps[datatype = bibtex]{
    map{%% 1. Find year in brackets and sort them as if they were without brackets
      step[fieldsource = year,
          match = regexp{A[(.+)]z}, final]
      step[fieldset = sortyear, fieldvalue = {$1}]
    }
    map{%% 2. Abbreviate an entry such as Adam J[ohn] Smith to Smith, Adam J.
      step[fieldsource = author,
          match = regexp{[[^]]+]},
          replace = .]
    }
    map{%% 3. Change US postal codes such as 'MA' to 'StateMA'
      step[fieldsource = location,
          match = regexp{,s*(MA|CA|NY)},
          replace = regexp{,~\State{$1}}]
    }
  }
}
% then change 'StateMA' etc. to AP style abbreviations 'Mass.' etc.
newcommand{State}[1]{csname State#1endcsname}
newcommand{StateMA}{Mass.}
newcommand{StateCA}{Calif.}
newcommand{StateNY}{N.Y.}

begin{filecontents}{jobname.bib}
@ARTICLE{western1889,
    AUTHOR = "Aug[ust] Western",
    TITLE = "Kurze darstellung des norwegischen lautsystems",
    JOURNALTITLE = "Phonetische Studien",
    YEAR = "1889",
    PAGES = "259--282",
    VOLUME = "2"}
@BOOK{lehiste1970,
    AUTHOR = "Ilse Lehiste",
    TITLE = "Suprasegmentals",
    YEAR = "1970",
    LOCATION = "Cambridge, MA",
    PUBLISHER = "The M.I.T. Press"}
@BOOK{hoff1946,
    AUTHOR = "Ingeborg Hoff",
    TITLE = "Skjetvem{aa}let",
    YEAR = "1946",
    LOCATION = "Oslo",
    NUMBER = "1",
    PUBLISHER = "Jacob Dybwad",
    SERIES = "Skrifter utgitt av Det Norske Videnskaps-Akademi i Oslo. II. Historisk-filosofisk klasse. 1946"}
@INCOLLECTION{hoff1968,
    AUTHOR = "Ingeborg Hoff",
    BOOKTITLE = "Aurskog og Blaker",
    EDITOR = "[Eyvind Lillevold]",
    TITLE = "M{aa}let i Aurskog og Blaker",
    YEAR = "[1968]",
    LOCATION = "[Aurskog og Blaker]",
    PAGES = "685--752",
    PUBLISHER = "Bygdeboknemnda for Aurskog og Blaker",
    VOLUME = "3"}
end{filecontents}
addbibresource{jobname.bib}

begin{document}
nocite{*}
printbibliography
end{document}