According to Feature S06: Optimization Minimum Background Sound, part 1 of the WELL Core requirements, the project team must install a sound masking system in open areas and enclosed rooms designated as quiet zones, circulation zones and in areas where workstations are present1. The sound masking system produces a uniform artificial sound that increases speech privacy between occupied spaces by reducing the intelligibility of speech and masking unwanted noises2. The other options are not as effective at maximizing speech privacy in conference rooms, as they either do not address the sound transmission between rooms (A and C) or increase the noise level in the adjacent spaces (B).
References: = Standard | WELL V2, Daylight modeling | WELL Standard