documentclass{article}
usepackage{tipa}
usepackage[T1]{fontenc}
begin{document}
  textipa{" ""}
end{document}

documentclass{article}
usepackage[ngerman]{babel}
usepackage[T1]{fontenc}
begin{document}
  "a "s "‘ "’ "< ">
end{document}

documentclass{article}
usepackage[ngerman]{babel}
usepackage{tipa}
usepackage[T1]{fontenc}
begin{document}
  textipa{"x""x"a"s}
end{document}

documentclass{article}
usepackage[ngerman]{babel}
usepackage{tipa}
usepackage[T1]{fontenc}
begin{document}
  shorthandoff{"}
  textipa{"a""s}
end{document}

documentclass{article}
usepackage[ngerman]{babel}
usepackage{tipa}
usepackage[T1]{fontenc}
  newcommand{myipa}[1]{shorthandoff{"}textipa{#1}}
begin{document}
  myipa{"x""x"a"s}
end{document}

documentclass{article}
usepackage[ngerman]{babel}
usepackage[T1]{fontenc}
  newcommand{shoff}{{shorthandoff{"} "a}}
begin{document}
  "a shoff{} "a
end{document}

documentclass{article}
usepackage[ngerman]{babel}
usepackage[T1]{fontenc}
  newcommand{shoff}[1]{{shorthandoff{"} 2"a #1}}
begin{document}
  1"a shoff{3"a} 4"a
end{document}

newcommand{myipa}{begingroupshorthandoff{"}myipaI}
newcommand{myipaI}[1]{tipaencoding #1endgroup}

shorthandoff{"}
section{textipa{"x""x"a"s}}
shorthandon{"}

newcommand{myipa}[1]{{shorthandoff{"}scantokens{tipaencoding#1endinput}}}