Echoed Voice deals damage. Its base power increases by 40 each
consecutive turn it is used but reaches a maximum power at 200.
However, the power will not increase during a round and will only
increase once per round (regardless of how many Pokémon used it). The
base power of Echoed Voice does not reset upon reaching its maximum.
When failing, the base power will still increase as long as the move
is executed, such as when it misses or is prevented by Protect.
BW-Battle Subway-36 BP
B2W2-Battle Subway, Pokémon World Tournament-18 BP
For other games:
And for the main question:
No, Round is when all the Pokemon in play use it...and Echoed Voice is when only the Pokemon using it will get the boost every turn. The 1st is 40 BP, and the top is 200 BP.