echo chamber(n = noun.artifact) - an enclosed space for producing reverberation of a sound;
is a kind of enclosure

   A room with walls that resonate sound, producing audible echoes; it is used especially to create special sound effects in recording music. [PJC]

N  resonance, ring, ringing, tintinabulation, reflexion, reflection, reverberation, echo, reecho, zap, zot, buzz (hiss), low note, base note, bass note, flat note, grave note, deep note, bass, basso, basso profondo, baritone, barytone, contralto, echo chamber, resonator, tinnitus, bell, doorbell, buzzer, gong, cymbals (musical instruments), sympathetic vibrations, natural frequency, coupled vibration frequency, overtone, resonating cavity, sounding board, tuning fork, tuning, squelch, frequency selection, resonator, resonator circuit, radio resonant structure, aromaticity, alternating double bonds, non-bonded resonance, pi clouds, unsaturation, double bond, (valence), resounding, resonant, reverberant, tinnient, tintinnabulary, sonorous, booming, deep-toned, deep-sounding, deep-mouthed, vibrant, hollow, sepulchral, gruff, sweet bells jangled, out of time and harsh, echoing down the mountain and through the dell.

air chamber, anechoic chamber, boron chamber, bubble chamber, burial chamber, chamber, chamber music, chamber of commerce, chamber orchestra, chamber pot, cloud chamber, combustion chamber, council chamber, cremation chamber, death chamber, echo, echo sounder, echo sounding, firing chamber, gas chamber, gun chamber, hyperbaric chamber, ionization chamber, lock chamber, piston chamber, presence chamber, radar echo, resonating chamber, spark chamber, star chamber, supply chamber, torture chamber, vacuum chamber, wilson cloud chamber