Microphones attached to a NASA-launched student balloon managed to capture alien sounds from the outer space. The United States space agency has not yet been able to determine the source of strange hisses. According to reports, infrasound frequencies of the sound that the ultra-sensitive microphones have captured are so low that a human ear cannot hear it.

As per reports published by The Independent, the balloon captured hisses, crackling sounds and whistles that are not hearable for a human ear. Researchers heard those sounds by speeding up the recordings of the infrasound. The space agency did not find the source of the sound, but there are many theories related to the strange sound.

As per the scientists, the strange sound could be because of the wind passing the path of the balloon. They also suggested that ocean waves or gravity waves could be responsible for the sound. Some other scientists said that the sound could be from the cable movements of the balloon.

To know the source of the sound, the space agency NASA has decided to explore the incidence more. The space agency has been planning to send a payload to capture more noises so that the source of the source of the sound can be found.

The earlier sound has been captured by Daniel Bowman, Chapel Hill’s University of North Carolina student. Bowman said, “For past 50 years, no acoustic recordings have been made in the stratosphere, and if the instruments are placed, something of importance can surely be discovered”.

According to Bowman, the helium balloon with the infrared microphones was sent in last year’s August above Arizona and New Mexico. Bowman said that sending the balloon was a part of his High-Altitude Student Platform study.