Nymph has bedroom that creates sound effects (4,7)
I believe the answer is:
echo chamber
'nymph has bedroom that creates sound effects' is the definition.
The definition suggests a singular noun which matches the answer.
'nymph has bedroom' is the wordplay.
'nymph' becomes 'echo' (figure of Greek myth).
'has' says to put letters next to each other.
'bedroom' becomes 'chamber' (synonyms).
'echo'+'chamber'='ECHO CHAMBER'
Can you help me to learn more?
(Other definitions for echo chamber that I've seen before include "part of recording studio?" , "Alternative to 7 [REVERB]" , "The Cavern might have provided?" , "Recording space creating reverberation" , "Space that reflects sound" .)