Those who have been seeing Nihira since some time now( in Aao Jhume Gaaein) would know that not losing sur is not new to her. When I read comments like "she looks expressionless, she is arrogant etc' I feel totally puzzled. What are we looking for...??
Way back in 1995 when Salilda died, Lataji sang a song remembering him from film Maya(1961) on doordarshan: tasveer teri dil me', this song has extremes of range, from the landing note to one octave up & down there is hardly any note which has not been used .... she looked like a stone while concentrating...there is no otherway these songs can be sung..!
Singers singing with eyes closed & fully focussed about singing are rarity today..I note there are many members who are music students..
I'm sure they will confirm that it takes years of riyaaz & blessings of Ma Sarswati(Goddess of music) so that one doesn't miss sur.
Ustad. Bade Ghulam Ali Khan once said of Lata Mangeshkar, "Kambakht, galti se bhi sur kharab nahi karti", same holds true for Nihira.
I think inability to control excitement & losing focus is most common reason(for trained voice) for going besura... hormonal response under stress/excitement can completely unsettle vocal cords.
Ujjaini is best example of this...
This is a singing contest & sur should be first consideration nothing else..
While other singers have suffered from common cold (which eliminated Keka), fever & fainting episodes, Nihira's sureela safar continues unabated...this is purely because of her focus & discipline
Go Miles Nihira...