Here is the full list of all 47 ECHO achievements.
Finish the game on Ultra Hard
Look at yourself in the mirror excessively
Complete the fifth Verse
Collect all Voices
Complete the first Verse
Traverse infinity for a while
Finish the game on any difficulty
Pick up every orb in every caste level
Collect 100 Voices
Take out a Hyper Echo
Shout and get the attention of 8 Echoes at once
Throw 20 Crystal Balls
Shoot 200 Echoes
Reach Chapter VI
Complete the fourth Verse
Get Foster back
Kill 3 Echoes by shooting a Sun
Line up and shoot 6 Echoes with a single shot
Tag 100 Echoes
Have Echoes know how to sprint, vault, use doors and walk in water at the same time
Reach Chapter V
Complete the third Verse
Collect 50 Voices
Get 4 additional Cell capacity slots
Take out 47 Echoes with the stealth takedown
Make a 2 cell energy drop during a blackout
Have Echoes play the harp and piano at the same time.
Collect a Voice by having an Echo strike it
Pick up 50 Suns
Distract 5 Echoes at once with one Crystal Ball
Use Area Scan 20 times
Play the whole piano piece during a blackout
Reach Chapter IV
Complete the second Verse
Collect 25 Voices
Kill 10 Echoes with Crystal Balls
Get 2 additional Cell capacity slot
Get an additional Cell capacity slot
Collect 10 Voices
Push 50 Echoes
Eat 20 pieces of fruit
Eat 5 pieces of fruit during a single blackout
Reach Chapter III
Push 5 Echoes at once with the Riot Gun
Push an Echo over a railing
Line up and shoot 3 Echoes with a single shot
Activate the palace