Contradiction with Amos 6:5
Nehemiah 12:8 speaks of praising God with musical instruments, while Amos 6:5 criticizes those who invent music for their own pleasure, suggesting a misuse of music.
Amos 6:5: That chant to the sound of the viol, [and] invent to themselves instruments of musick, like David; [chant: or, quaver]
Contradiction with 1 Samuel 16:23
Nehemiah 12:8 involves Levites praising with music; whereas, in 1 Samuel 16:23, music is used to soothe Saul's troubled spirit, indicating a different purpose.
1 Samuel 16:23: And it came to pass, when the [evil] spirit from God was upon Saul, that David took an harp, and played with his hand: so Saul was refreshed, and was well, and the evil spirit departed from him.