Background: Ram Narayan was born on 25 December 1927 in Amber village, near Udaipur in northwestern India. His great-great-grandfather, Bagaji Biyavat, was a singer from Amber, and he and Narayan's great-grandfather, Sagad Danji Biyavat, sang at the court of the Maharana of Udaipur. Narayan's grandfather, Har Lalji Biyavat, and father, Nathuji Biyavat, were farmers and singers, Nathuji played the bowed instrument dilruba, and Narayan's mother was a music lover. Narayan's first language was Rajasthani and he learned Hindi and, later, English.
Context: Narayan increased the status of the sarangi to that of a modern concert solo instrument, made it known outside of India, and was the first sarangi player with international success, an example later followed by Sultan Khan. Narayan's simplified fingering technique allows for glide (meend) and affected the modern sarangi concert style, as aspects of his playing and tone creation were taken up by sarangi players from Narayan's recordings.  Narayan taught at the American Society for Eastern Arts and the National Centre for the Performing Arts in Mumbai in the 1970s and 1980s, where he gave the first master class for sarangi. Narayan privately trained sarangi players, including his daughter Aruna Narayan Kalle, his grandson Harsh Narayan, and Vasanti Srikhande. He also taught sarod players, including his son Brij Narayan, as well as vocalists and a violinist. In 2002, he taught 15 Indian students and more than 500 students in the United States and Europe had studied with him. Indian music in performance: a practical introduction, released in 1980 by Neil Sorrell in cooperation with Narayan, was described as "one of the best presentations on modern North Indian music practice" by Hans Neuhoff in Musik in Geschichte und Gegenwart.  Narayan argued that appreciation of the sarangi and him came only after acknowledgment by the Western audience. He attributed the lack of sarangi students to a lack of competent teachers and said that the Indian government should assist in preserving the instrument. The Pt (Pandit) Ram Narayan Foundation in Mumbai awards scholarships to sarangi students. Narayan has stated he was skeptical the sarangi would survive and said he would never give up promoting the instrument.  Narayan received the national awards Padma Shri in 1976, Padma Bhushan in 1991, and Padma Vibhushan in 2005. The Padma Vibhushan, India's second highest civilian honor, was presented by Indian President A. P. J. Abdul Kalam. Narayan was awarded the Rajasthan Sangeet Natak Akademi Award for 1974-75 and the national Sangeet Natak Akademi Award for 1975, and was made a fellow of the Rajasthan Sangeet Natak Akademi for 1988-89. He received the Kalidas Samman from the Government of Madhya Pradesh for 1991-92 and was presented with the Aditya Vikram Birla Kalashikhar Puraskar in 1999 by P. C. Alexander, governor of Maharashtra. He received the Rajasthan Ratna for 2013, was awarded the Lifetime Achievement Honour - Classical at the 4th Gionne Star Global Indian Music Academy (GiMA) Awards 2014, and was awarded the Pandit Bhimsen Joshi Lifetime Achievement award for 2015-2016 in the field of classical music by the government of Maharashtra. The biographical film Pandit Ramnarayan - Sarangi Ke Sang was shown at the 2007 International Film Festival of India.
Question: When did he begin to use steel strings on his instrument?. Whats the answer?