It started when her brother-in-law bought her a tape recorder and encouraged her to do something for the blind.
Ms Singhal (left) depends on charity and private contributions
Now 46-year-old Madhu Singhal, herself visually impaired, runs an audio library of 16,000 works in the southern Indian city of Bangalore.
Unlike in the West, audio libraries are rare in India, and "talking books" are rarely available in shops.
Ms Singhal's library has audio books in English and two Indian languages, Hindi and Kannada.
"I wanted to take books to blind people," says Ms Singhal, who is also a founder of the Mitra Jyothi (Friendly Light), a city-based non-governmental organisation.
"We started [recording] fiction but moved on to academic material when we were flooded with requests," says Ms Singhal.
She depends entirely on volunteers to help with the recordings.
Two recording rooms at Mitra Jyothi's office are the hub of the library.
Volunteers - from young students to housewives and the retired - lend their time and voices to record for the blind.
One of the volunteers is 68-year-old Nityanand.
"I spend every afternoon recording at least two tapes a day," says Nityanand.
For a nominal sum of 10 rupees, the visually impaired can enrol as members.
Nagaraj, 23, who is doing his master's degree at the local university, is one of several hundred members who use the library.
"I use both Braille and tapes. But [audio books are useful] because you can rewind the tape and listen to the lesson over and over again.
"I have been getting first class grades from the time I started using the material."
With word about the library spreading, students from neighbouring southern states have begun demanding audio books in their native languages.
Student Nagaraj (left) says his grades have improved
The library's success has motivated Ms Singhal to start a computer centre and an employment centre for the disabled.
But she has to depend entirely on private contributions and charities to run the operations.
"I need lots of audio cassettes, computers and a building of our own, she says.
Her efforts to get government aid have not yet yielded results.
But thanks to the untiring efforts of Ms Singhal and her volunteers, this unique library is continuing its good work.