'Laurel' or 'Yanny'? What's the difference?

An online audio clip has puzzled internet users, going viral on the internet after being posted by a US high school student on social network Reddit.

Some insisted they heard "Laurel" each time they listened to the clip, while many others argued only "Yanny" could be heard, no matter how many times they tried.

The initial version of the audio was recorded by the original poster at a vocabulary website, according to the Paper.cn.

The audio was also posted on China's twitter-like Sina Weibo. The official Weibo account of People's Daily posted the audio, and the post got 1,977 likes, 1,424 comments and 1,865 reposts in the hours after its release on Friday.

A weibo user named JiYuCtrip said "if you hear 'Yanny', please click the like on my comment," and that comment had received 1,656 likes by 12:49 pm. Another Weibo user named Jiuxiangnanxiang said, "It's 'Laurel'." This comment got 801 likes.

However, Pikachu-u, another Weibo user, said "isn't it 'Yarel'?"

But there's no need to be confused, or question your own hearing.

Abby Walker, a linguistics professor from Virginia Tech University, was quoted by the Paper.cn as saying there are two main reasons for the phenomenon. One is people's hearing differences and the other is the speaker equipment. In either case, it depends on one's ability to receive high-frequency or low-frequency sound waves. People who hear "Yanny" mostly receive high-frequency sound waves in the audio, and people hearing "Laurel" receive low-frequency ones.

Walker added people may hear different words if the audio's pitch is adjusted.

Bridget Carey, a sci-tech reporter with CNET, was quoted by the Paper.cn as saying people who are hearing-impaired, usually caused by aging or excessive use of earphones, will find it hard to hear "Yanny".