Nah, the a and the o have different tones. If it were đáo, it would be an "ow" sound with a high tone. In the audio it's clearly a with a high tone and o with a dipping tone.
Even if you think that the speaker is combing the two sounds, the position of your mouth is different from đáo.
Pedantic about English but still present uncomfortable translation. The viet says "yesterday you were where." The direct translation is okay English and helps me understand and anticipate sentence construction. Nut failed "Yesterday where were you is okay but not a native speakers phrase. "Where were you yesterday " is a much more likely expression