The new instrument, a rattle called the caxirola, creates sound pressure levels similar to normal conversation, according to researchers from the Federal University of Santa Maria in Brazil.
Presenting their findings to the Acoustic Society of America in San Francisco on Thursday, the experts said it would take about 2,000 of the maracalike caxirolas to emit the same noise as one vuvuzela.
"The caxirola is not so dangerous as the vuvuzela for the people who are going to be in the stadiums," said Bernardo Murta, one of the researchers.
The incessant buzzing from the long, skinny horns was so loud that players had a hard time communicating, and many TV viewers initially thought there were reception problems.
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There may, however, be another problem with the caxirola that has nothing to do with volume.
After it was introduced at a match in Brazil this year, hundreds of disgruntled fans hurled the plastic instruments onto the field when the game became a blowout.
"So it's not dangerous to our hearing but for our safety," Murta said.