Amulet of yakspeak is an item released with the 2015 April Fools event. It was a common drop from yaks. It did not allow players to talk to pack yaks despite the name. Instead, it would turn all conversations with non-voice acted non-player characters into variations of "Baroo Barooo!". This is voice acted.
The audio did not discriminate based on gender, thereby using female audio with male characters and vice versa.
One audio clip from the amulet's dialogue is a reference to The Muppet's Mah Nà Mah Nà song, in which the audio still plays the song, but the Mah Nà Mah Nà portion is replaced with "baroo baroo".
One audio clip features Mod Moltare reciting the poem, "Roses are red, violets are blue, I'm a pack yak, baroo baroo."
Sometimes, after telling Juna a story to enter the Tears of Guthix cave, her response to the story is not affected. All following dialogue, as well as the story itself, is changed into some variation of "Baroo baroo".
Advisor Ghrim's message of your items being delivered to your bank when collecting from Managing Miscellania is unaffected, as well as the message before he shows how your subjects are distributing their efforts.