The acoustics of the Nave were very important to the designers – in the days before loudspeakers a speaker's voice needed to carry throughout the Nave. The larger space over the Nave is ‘tuned’ to a reverberation time of about 1.5 seconds, while the Sanctuary space offers the musicians a more satisfactory 7.5 seconds. The plywood tetrahedra in the Nave ceiling are part of the acoustic scheme. The cathedral now has a modern loudspeaker system and T Loop, and the acoustics have been described as 'first-rate'.