adverb, adverb taking the 'to' particle
noisily; bleatingly
Mimetic word for a loud, high-pitched, often continuous noise, such as bleating, crying, or a shrill alarm. Often used with と or as an adverb.
赤ちゃんがびいびい泣いている。
The baby is crying loudly.
警報がびいびいと鳴り響いた。
The alarm rang out shrilly.