I attended a Tenebrae service tonight for Holy Week. Very moving. Some great music for organ and choir, including the "Libera me" from Faure's Requiem, which as a whole is one of my favorite works of music and definitely a desert-island disc. (The "Sanctus" and "Agnus Dei" are especially wonderful.) As the service progresses, there is a diminution of light; altar candles are put out one by one, and someone flicks the switch on the sanctuary's lights as well.
In the end, we're left with a single candle in an otherwise dark church, and from the choir balcony comes the strepitus a loud clatter intended to evoke the earthquake that was said to happen at the moment of death. Having never heard it before, I was a little skeptical. At tonight's service, they used loud dissonance on the organ and some unseen metal sheets to create the strepitus. The church was entirely dark, except for a few tiny votives off to the side. A few headlights from outside traced their way through the nave at one point. The noise continued and seemed to grow louder. The combined effect was really quite affecting. Eventually, the lights were turned on. We all left in near silence.