In August, American and Canadian diplomats working in Havana reported hearing sounds that were believed to be a mysterious sonic weapon.
Doctors termed the sounds ‘directional acoustic phenomena’, and even noticed brain changes in those hearing it.
While a study by Cuban scientists last week suggested that the sound was produced by crickets, an expert claims that this isn’t the case.
Instead, he says that both the sounds and health effects may be the result of a beam of pulsed microwaves.
In a study in the IEEE Microwave Magazine, Professor James Lin, an expert in Electrical Engineering at the University of Illinois at Chicago, suggests that microwaves produced the sounds.
Professor Lin said: ‘A minuscule but rapid rise in tissue temperature, resulting from the absorption of pulsed microwave energy, creates a thermoelastic expansion of brain matter.’
Professor Lin suggests that the resulting acoustic wave may be perceived as sound.
And the brain tissue damage seen in the diplomats could have been caused by a combination of heating and shock waves.
While Professor Lin is unsure of what kind of device could cause this microwave auditory effect, he says development is ‘always a possibility by some military-related organisations.’
But not everyone is so convinced by Professor Lin’s theory.
Speaking to New Scientist, Professor Kenneth Foster, professor of Bioengineering at the University of Pennsylvania, said: ‘That theory is a real stretch.
‘It would require something like a major airport radar transmitter with the subject’s head close to the antenna in its direct beam. I guess it is possible, but not likely.’
Last week, a report issued by a board of Cuban scientists suggested that crickets are the unlikely culprits of the brain-changing sounds.
While US officials did not provide sound recordings to the scientists, Carlos Barcelo Perez, an environmental physicist at the National Institute of Hygiene, Epidemiology and Microbiology, recorded evening sounds around the residences, according to Science.
The recordings revealed that the biggest noisemakers were insects.
In particular, he found that the Jamaican field cricket chirps at a frequency matching the sound on the recordings, which topped out at 74.6 decibels.
Medical experts discovered changes in the brains of US and Canadian diplomats, which fuelled growing scepticism that some kind of sonic weapon was involved.
Medical testing revealed the embassy workers developed changes to the white matter tracts.
Speaking to DailyMail.com, Dr Joel Moskowitz, a community health professor at the University of California, Berkeley, said: ‘This makes me think the victims may have developed electromagnetic hypersensitivity (EHS) from exposure to electromagnetic fields in the embassy.
‘This happened during the Cold War to personnel stationed in the US embassy in Moscow when the Soviets were bombarding the embassy with microwaves to monitor oral communications in the ambassador’s office.’
Loud, mysterious sounds followed by hearing loss and ear-ringing had led investigators to suspect ‘sonic attacks.’
But the Cuban report suggests that the ‘sonic attacks’ were really just crickets.
Doctors still don’t know how victims ended up with the white matter changes, nor how exactly those changes might relate to their symptoms.
The FBI is now planning its own investigation, to confirm whether or not crickets were causing the sounds.