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These are not easy to say! (th+s)
bathes [beiðz]
baths [ba:θs]
clothes [klouðz]
cloths [klɔθs]
months [mɔnθs]
mouths [mauðz]
depths [depθs]
lengths [leŋθs]
widths [widθs]
Sounds from http://www.howjsay.com/
For more information about 'silent letters' in US English: http://evaeaston.com//sl-pat-pb.html
or more information about voiceless and voiced sounds : http://evaeaston.com//p-b-pattern.html