This may well come down to House Rulz, but my druid recently acquired a Belt of Dwarvenkind, and I was wondering if (assuming you would let him wear it in bear shape), you would also let him speak Dwarvish.
I realise that according to the description of Wild Shape in the PHB: You can’t cast spells, and your ability to speak or take any action that requires hands is limited to the capabilities of your beast form. (p. 67).
I also see the following points made in answer to Can a druid speak while in wild-shape?:
A DM may rule that a high-level druid has some capacity for speech in beast form based on being able to perform verbal spell components with the 18th level class feature Beast Spells:
Beginning at 18th level [...] You can perform the somatic and verbal components of a druid spell while in a beast shape ... (id.) But, this would be a houserule and likely not intended by RAW since Beast Spells specifically limits the verbal aspect to druid spells (not all spells).
The inability to form words (i.e., communicate in a language) in beast form would not prevent you from "gain[ing] the ability to comprehend and verbally communicate with beasts for the duration" pursuant to Speak With Animals (PHB, p. 277).
So my reverse-logic is this: Since a player-character can Speak with Animals due to the influence of magic, couldn't a beast (say a bear) speak Dwarvish when under the influence of a Belt of Dwarvenkind?