"An t-eun beag."
Translation:The small bird.
Well, both eu and èa in Gaelic are pronounced as /ia/, and then the speaker voices the stops after nasals – that’s a typical feature in many dialects of Gaelic.
See this discussion about an cù the dog sounding [əŋ ɡuː] with voiced [ɡ], and the Akerbeltz article Nasalisation 2 or Why am I married to ə NɯNʲə agam?, and Scottish Gaelic phonology: Nasalisation on Wikipedia.
There still should be a difference between an t-eun with voiced [əN dʲ(ʰ)ian] vs dèan with voiceless unaspirated [tʲian].
For some speakers there would also be a difference after nasals: between an t-eun the bird with aspiration [əN dʲʰian] vs an dèan mi? will I make? without it [əN dʲian mi], or in Lewis with full nasalization: an t-eun [əNʲhian] vs an dèan…? [əNʲian].