Researchers have developed a device that can automatically identify autistic children as young as 24 months using the vocalizations they make during a normal day at home. Instead of waiting months or years for an appointment with a specialist, parents could get an objective diagnosis by mail in a couple of weeks.

According to a recent study from researchers at Washington University in St. Louis, the average age of diagnosis for autism is 5.7 years old -- several years after such a diagnosis is first possible. With the new system, developed at the LENA Foundation, diagnosis takes just a few weeks. "Intervention is most effective when the child is two to four years old," says Jill Gilkerson, director of child language research at the LENA Foundation.

The foundation says its tool can distinguish, with 91 percent accuracy, between a child developing normally, a child with autism, and a child with unassociated language delays.

The home kit, called LENABaby, hit the market earlier this month and consists of a questionnaire regarding the child's development, a digital audio recorder, and an outfit for the child to wear. First thing in the morning, the parent puts the outfit on the child and slides the recorder into a pocket on the front. The recorder is left on all day so that it can capture up to 16 hours of audio. At the end of the day, the parent removes the device from the pocket and sends it to the foundation, where the LENABaby software can analyze the data.

"Roughly speaking, autistic children vocalize differently from other children," explainsDongxin Xu,manager of software and language engineering at the LENA Foundation. While this concept isn't new, clinicians have had a hard time using it to their best advantage when making a diagnosis. The problem is, in part, logistical: with existing methods, it is hard to collect enough good-quality data.

Gilkersonsays that most traditional assessments take less than four hours. LENABaby, in contrast, considers a full day of activities in the child's natural environment. Traditional assessments can be done in the child's home, but this often involves multiple video cameras and lights, which can influence the child's behavior.

Even if enough data is gathered, analyzing the audio is still extremely difficult and time-consuming. Making a diagnosis isn't as simple as counting the number of times the child makes a certain kind of sound, explains Jeffrey Richards, a statistician and database technician for the LENA Foundation.