Background: Later, during the Koine Greek period, the aspirated and voiceless stops /tʰ d/ of Attic Greek lenited to voiceless and voiced fricatives, yielding /θ ð/ in Medieval and Modern Greek.
Question: Attic Greek lenited to what?
Answer:<extra_id_0>.
<extra_id_0> voiceless and voiced fricatives<extra_id_1>