Theory:

     The sound of the shehnai began to be considered auspicious. And for this reason it is still played in temples and is an indispensable component of any North Indian wedding. In the past, the shehnai was part of the naubat or traditional ensemble of nine instruments found at royal courts. Till recently it was used only in temples and weddings. The credit for bringing this instrument onto the classical stage goes to Ustad Bismillah Khan.
Explanation:
 
The sound of the shehnai was liked by all and was considered auspicious, or promising to bring good fortune. It is played in all temples till today because it is considered auspicious. There cannot be any North Indian wedding without shehnai music as it has become absolutely necessary. During the olden times, shehnai was a part of the group of nine instruments in the palace, called the naubat. From temples and weddings, shehnai has reached the classical music stage - only because of Ustad Bismillah Khan.
 
Meanings of difficult words:
 
No.
Word
Meaning
1
auspiciouspromising to bring good fortune, luck
2
indispensablenecessary, cannot be without
3
ensemblethings considered as a group
Reference:
National Council of Educational Research and Training (2006). Beehive. The Shehnai of Bismillah Khan (pp. 21-29). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.