A new survey has found that about 1 percent of children have symptoms of listening difficulties, or LiD, according to researchers at the Japan Agency for Medical Research and Development.

The symptoms include an inability to understand what has been said or to frequently mishear things, even though hearing tests show no abnormalities.

The paper detailing the first large-scale epidemiological study in Japan was published online on Nov. 30 in the International Journal of Pediatric Otorhinolaryngology.

LiD is thought to be caused by a disorder in the brain’s processing and understanding of sound information that comes through the ears.

HEARING BUT NOT UNDERSTANDING

Two years ago, Ayako Ura, who lives in Osaka, noticed something “unusual” about her two daughters.

The oldest daughter, 11, an elementary school student, often got into disputes with her classmates.

When Ura asked her why, her eldest daughter's explanation changed several times. Ura scolded her every day to stop lying, and her relationship with her daughter reached a new low, she said.

The daughter also fell asleep in class and did not do her homework.

One day, Ura noticed that her second daughter, 7, froze on the spot when Ura quickly told her to “get dressed.”

The 7-year-old said, “I can hear you, but I don't know what you are saying,” Ura recalled.

With these words as a guide, she searched the internet and learned about LiD, Ura said.

She took them both to see a doctor, realizing that the symptoms listed online as examples, such as “not understanding long stories” and “asking for words to be repeated too often,” also applied to her eldest daughter.

Upon examination, both were diagnosed with LiD. They were also found to have developmental disabilities that contribute to the hearing impairment.

The two daughters now have hearing aids, which help them focus on important sounds by utilizing the noise-reduction feature.

“I’m glad we were able to recognize LiD at such a young age,” Ura said. She said she hopes more people will learn about it.

NEGATIVE IMPACT IF UNDIAGNOSED

Overseas, it has been reported that 0.2 to 5 percent of the population have symptoms. Although it was not well known in Japan, knowledge of it has spread through social media over the past few years.

The researchers in the study conducted a questionnaire survey of 4,350 children attending nine elementary, junior high and high schools in the Kansai region and their parents or guardians from 2021 to 2022.

Each of the 743 respondents answered questions related to LiD, such as, “I mishear things a lot,” as well as questions related to their development.

The results showed that 12.4 percent of the respondents said the frequency of them having LiD symptoms is “slightly high,” 2.8 percent said “moderately high” and 0.8 percent said “considerably high.”

While the percentage increases with the child’s grade level, parents tended to underreport symptoms, revealing a structure that makes it difficult for others to recognize the impairment.

In addition, 10 percent of the parents reported that their child had developmental problems, and the more severe the LiD symptoms, the higher the score of developmental problems tended to be.

A previous domestic study found that 34 percent of people who are aware of LiD have ADHD (attention deficit hyperactivity disorder).

“At least the 0.8 percent people with a fairly high frequency of symptoms are likely to be diagnosed with LiD,” said Hirokazu Sakamoto, associate professor of otorhinolaryngology at Osaka Metropolitan University, who led the research.

“It can have a negative impact on a child's learning and language acquisition, and a diagnosis is needed for action to be taken as early as possible,” he said.

As it is difficult for parents to recognize the LiD symptoms in their children, experts are working to develop diagnostic criteria.

Research on LiD began in the 1950s in Europe and the United States, and diagnostic guidelines have been prepared. However, interest in the impairment in Japan is low, and there are only about 20 medical institutions in the country that can diagnose it.

In addition, testing and diagnosis can take a long time, and listening difficulties are often challenging to replicate under certain conditions.

There is no fundamental cure for the disorder, with the use of hearing aids and note-taking being the most common remedies.

The researchers at AMED are in the process of developing common diagnostic criteria to increase the number of physicians who can diagnose it.

They also recommend issuing medical certificates to request reasonable accommodations for those with LiD, visualizations of speech, earphones and hearing aids to reduce ambient noise, and more doctors and medical institutions that can accommodate such requests.