Summary Box: Toyota to sell noise maker for Prius, allowing pedestrians to better hear hybrid

Summary Box: Quiet Prius will have noisier option

WHEN QUIET IS A PROBLEM: Hybrid cars, powered by a combination of gasoline and electric motors, can run on electricity and are far quieter than cars with traditional gasoline engines. That has drawn complaints that there is an increased risk of pedestrians being hit, especially blind people.

A SOLUTION THAT HUMS: Toyota Motor Corp. will offer an optional speaker system that makes a humming noise about as loud as a normal car, on the popular Prius hybrid. Sales will start Aug. 30 in Japan, and the company is looking at bringing it to the U.S. and making it available on other hybrid models.

THE PRICE TAG: 12,600 yen, or about $148, excluding installation.