The speculation of a sonic attack gained momentum when US personnel in Cuba recorded a high-pitched drone, and then released the audio to the Associated Press. Exams of the diplomats revealed signs of concussions and other brain injuries, which was thought to have been caused by a weapon that released microwaves. On Friday, scientists showed evidence suggesting the sounds were that of very loud crickets.
The two scientists did not rule out the prospect of the diplomats being attacked, but said the audio recording was not a sonic weapon as previously suggested.
Scientists Alexander Stubbs of the University of California Berkeley and Fernando Montealegre-Z of the University of Lincoln in England looked at the audio recordings made by the US diplomats.
In a phone interview Mr Stubbs said: “There’s plenty of debate in the medical community over what, if any, physical damage there is to these individuals.
“All I can say fairly definitively is that the AP-released recording is of a cricket, and we think we know what species it is.”
The results of their analysis was presented at the annual meeting of the Society of Integrative and Comparative Biology.
The two scientists published an earlier version of their study online and plan to submit their paper to a scientific journal in the coming days.
Mr Stubbs had come across certain insects while doing field work in the Caribbean, which reminded him of the sounds in the audio recording.
When the two scientists listened to the recording they found the acoustic patterns were similar to the songs from particular insects.
During courtship male singing insects produce certain acoustic patterns, and females are attracted to certain males because of their songs.
This has led to the evolution of different songs in different species of insect.
The two scientists concluded that if the sounds heard by the US diplomats were insects then it could be possible to pinpoint the species of insect.
Looking for a match they analysed field recordings of North American insects found on a database at the University of Florida.
What they discovered was a similarly of the sounds to that of the Indies short-tailed cricket.
The cricket sound is different to the sounds in the recording slightly, which the scientists attributed to an artefact of the recording.
This may be due to the fact the diplomats recorded the sounds inside and the scientists recordings were made in the field.
The scientists then studied the cricket recording in a house, which echoed a pattern more similar to those in the recording.
The scientists wrote in their analysis that the Indies short-tailed cricket “matches, in nuanced detail, the AP recording in duration, pulse and repetition rate, power spectrum, pulse rate stability and oscillations per pulse.”