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Venetian Acoustics Rediscovered

1 November 2011 5:22 pm
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Hans A. Rosbach/Wikimedia

Renaissance beauty. The Redentore Church in Venice looks pretty when empty, but it had better acoustics when full, according to a new study.

The wealth and artistic sensibility of Renaissance Venice nurtured great musical innovations. Complex polyphonic, or multipart, music and the novel coro spezzato, or split choirs, were written for festivals and performed in the city's grand basilicas. But the Venetian basilicas and giant churches that still stand today have terrible acoustics for that kind of music. The subtleties of polyphonic music and the spatial "stereo" effect of the split choirs are jumbled and lost in the rumbling echoes of the vast, lofty chambers. With acoustics blurring the special effects, how could Renaissance audiences have appreciated the music?

There are two answers to that question, according to a new analysis by music technologist Braxton Boren of New York University and physicist Malcolm Longair of the University of Cambridge in the United Kingdom. Boren and Longair created computer models of two famous Venetian venues and their acoustics and presented the results this week at the Acoustical Society of America Meeting in San Diego, California.

The two obtained detailed acoustical measurements for the famously beautiful Basilica of San Marco and Palladio's Redentore, both in Venice. They used the measurements to construct acoustic models of the two churches on a computer. After consulting with architectural historians, they calculated the acoustical properties of the tapestries, wooden chairs, and crowds of people that would fill the churches on a festival day, when polyphonic and split choir music would be performed.

The results are striking. Boren and Longair found that the acoustic attributes of the churches not only change significantly when they are decorated for festival days and filled with people but also are best at the seat of the richest man in the house.

Today, the reverberation time, or the amount of time it takes a sound to decay to inaudibility, is almost 7 seconds in the modern San Marco and slightly more in the Redentore when the churches are empty. Such long reverberations blur polyphonic music and ruin the effect of the split choir. But on festival days, filled with decorations and people, the Redentore's reverberation time was cut in half. This would have made polyphonic music clearer but somewhat quieter.

The results for the Basilica of San Marco were even more interesting. San Marco has a special seat for the doge of Venice, the city's most senior elected official, who sat at the front of the church near the altar. There is no direct line of sight between the original balconies music historians assume were used for split choirs and the doge's seat. The sound bounces off a wall and a floor, delaying the arrival of the sound and lessening the volume. The other concert attendees, who sat behind the doge, would have had even worse sound quality. But a modification built by architect Jacopo Sansovino in the 16th century apparently would have made the doge's seat worthy of a modern concert hall. These raised galleries, called pergoli, may have accommodated the split choir. Boren and Longair's model finds that if the split choir was indeed in the pergoli, and if the basilica is decorated and filled with people for festival day, the reverberation time at the doge's seat is between 1.5 and 2 seconds. That's considered the ideal for hearing a concert at its best.

To listen to these effects, visit this Web site and scroll to the bottom of the page. The top button plays a recording of polyphonic music as it would sound in an echoless chamber; the middle recording is of polyphonic music as it would sound in the empty Basilica of San Marco; and the bottom one is of polyphonic music in the basilica during a festival, as predicted by Boren and Longair's computer model.

"Braxton's work provides fresh insight on the acoustics of large Venetian churches through the use of modern computational simulation techniques," says David T. Bradley, a physicist at Vassar College in Poughkeepsie, New York. "His computational approach, married with historical evidence, allows him to recreate the aural environment as it would have occurred during the Renaissance, giving us an acoustic view into the past."

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