The findings, reported by newspaper Schweiz am Sonntag, came as part of a doctoral dissertation carried out by agricultural scientist Julia Johns and a fellow researcher at the top-flight Swiss Federal Institute of Technology in Zurich (ETHZ).
The pair strapped 5.5kg bells to more than 100 cows in 25 farms across the country and monitored their activity, head movements, reactions to sound and feeding behaviour during a series of experiments.
They concluded that cow bells can create noise levels of up to 113 decibels, the same as a chainsaw or a pneumatic drill and well over the legal limit of 85 decibels.
According to the researchers, it’s possible that thousands of cows – whose hearing is more sensitive than a human’s – have already been made deaf through wearing a bell.
Speaking to Schweiz am Sonntag, project manager and ETHZ scientist Edna Hillmann said some of the 100 examined cows were unresponsive to sound.
“In humans we would expect a hearing impairment to develop after being exposed to this high noise for a certain length of time,” Hillmann told the paper.
The bells can also affect the feeding behaviour of cows, leading them to chew the cud for less time than cows not wearing bells, according to the study.
“But what has the greater influence – weight or sound – is not yet clear,” said Hillmann.
The study hardly comes as a surprise to animal rights groups, who have long criticized the impact of cow bells on bovine welfare.
Reacting to the news in daily Le Matin, Lolita Morena of the Swiss animal protection group said: “We didn’t need long university research to tell us that the bells are not beneficial to cows.”
Calling for a ban on the bells, which are primarily used by farmers to locate cattle grazing on alpine pastures, Morena said: “Farmers will just have to spend a bit more time finding their cows in bad weather, like shepherds do. It’s difficult work… but they chose it.”
Farmers have scoffed at the suggestion of the researchers to attach GPS trackers to cows instead of bells, saying that reception in alpine areas would be patchy at best.
“In this IT age we could replace the bell with a microchip and the farmer could then locate his cattle using a smartphone,” researcher Johns told Schweiz am Sonntag.
“They can’t be serious,” responded Jacques Bourgeois, director of the Swiss Countryside Union, in Le Matin. “These researchers have completely missed the point. I wonder if they’ve even stepped out of their lab and been to the mountains.”
Bourgeois also pointed out that the heavy bells studied by the pair are only ever used for ceremonial occasions.
“It’s only one day a year that cows wear size 31,” he said, referring to the 5.5kg bells.
“It’s part of our culture, our traditions and it contributes to the beauty of our alpine areas,” he added.
For Swiss Tourism, Switzerland without cow bells is not inconceivable, but “It would be the end of a myth, of an image of Switzerland,” said spokesperson Véronique Kanel.
"However, our mountains also have other assets, including silence, which is what people are also seeking when they go to the Alps."
Should experts unanimously agree that bells harm the cows then they would accept the decision to ban them, said the organization, as “animal welfare is paramount.”
Commenting on the project, the federal food safety and veterinary office (BLV) said it had “noted with interest” the new findings, reported Le Matin.
“No study to date has examined in a serious and systematic manner the effects of bells on the well-being of cows,” it said.
Ceremonial bells will be on show in parts of the country this weekend during the annual parades of cows returning from the high alpine pastures to the village farms.
The popular désalpes in Charmey, in the canton of Fribourg, and St-Cergue in the canton of Vaud, both take place on Saturday September 27th.