use the printf command.
http://manpages.ubuntu.com/manpages/intrepid/man3/printf.3.html
you can wrap it in $() to use as a variable if needed, too.
For example,
echo $(printf '\u02BBUtthay\u0101n h\u01E3ng Ch\u0101t Khao Yai')
this outputs: ʻUtthayān hǣng Chāt Khao Yai
Hope that helps.