The Associated Press (AP) has obtained a recording of the tones that some US Embassy workers in Havana, Cuba heard in a series of incidents that began in 2016, and that the US government believes could have been caused by a sonic attack, according to the AP article.
The origin of the original sounds are still unknown, despite analysis by the US Navy and intelligence services, according to the AP. 
The sound sample obtained by the AP, deemed safe for listening online, is comprised of 20 or more different frequencies that pulse in varying lengths. However, as the AP article points out, very high or low frequencies may not be picked up by conventional tools used to measure sound; the recording may only be part of what Embassy workers heard.
Currently, 22 workers have been “medically confirmed” as affected by the sounds, according to the US State Department. Earlier reports had said workers suffered from symptoms like tinnitus, dizziness, and headaches, among other symptoms, after exposure to the sounds.
To read the article in its entirety and to hear a sample of the sound, please visit the AP website here.
Source: AP