I need a document in which I can write the international phonetic alphabet (ipa) characters without interfering with italics.
Please use the IPA package.
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{ipa}
\begin{document}
% Package fontenc
\ae % æ
\dh % ð
\ng % ŋ
% Package ipa. It is also named wsuipa.
\nitheta % θ
\esh % ʃ
\yogh % ʒ
\niepsilon % ɛ
\openo % ɔ
\invv % ʌ
\schwa % ə
\stress % vertical stroke (superior) ˈ
\secstress % vertical stroke (inferior) ˌ
% Overlap
\eth % ð
\eng % ŋ
\end{document}