From Newsgroup: rec.arts.anime.misc

It's a challenge to hear the dog whistle Beato simulates in the episode
10 "case22 Comfort Comrad" of Princess Principal. Because human's
hearing for high-pitched sound gets poorer as he/she becomes older. If
you are 40 or younger, you could hear the sound clearly. I wonder
whether Masaki Tachibana, the director, himself could hear the sound
very clearly.
--
/ Ishikawa Kazuo /
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