rshankar: I am reproducing the text from the site that you could not access.:
Lehra (lehra = ripple, a small wave - in hindustani)
For solo performances on rhythm instruments such as the tabla as also for solo dance items, a recurring tonal pattern encompassing a predetermined number of beats is cyclically supplied in a required tempo on the sarangi, harmonium, violin or some such melodic instrument. This repeated pattern is known as lehra.
The essence of a lehra is its constancy and sequentiality intended to provide a firm reference. It is not musically/melodically elaborated, even though a lehra player occasionally may tend to add a few embellishments to the melodic frame. It is untiringly presented as a reference circle to the solo player as per his/her directions. It truly consists of a minor musical wave.
Vocal lehra is a theoretical possibility but rerely exploited in music.
Hmm.. from the definitions above, it doesnt seem that there is an equivalent in karnatic music. Karnatci has a construct in Tani, which is reserved for the percussionists, whereas hindustani has none like that and they seem to employ lehera to lend the percussionist scope for displaying his skill
Occasionally artists like Chaurasia, Shivkumar Sharma give a lehera like touch to their renderings by repeating a few lines for the sake of their distinguished percussionists.
Like here in these few seconds worth.
two songs with the word leher are unforgettable, they are leheron ki leher,ulfat hain jawan by Hemant kumar and the background score of it,2) dil me ek leher, an alltime favourite ghazal of Ghulam Ali, in how many pleasant ways the word leher is repeated, an appreciation by coolkarni in his inimitable way is welcome gobilalitha
is it not there in the pure-rhythm parts of kathak dance too?
It is certainly a great help to understanding the long cycles of Hindustani music.
It would be an interesting experiment in 'fusion' (it's probably been done) to introduce it to the Carnatic thani, just to see how it sounds. I suspect that it would go better with those who do not emphasise the nadam aspect of mridangam, rather than those who do.
as a previous sarangi amateur I can add to the definition given above that these 'tonal patterns' always stay in raga, and that the old sarangiyas knew hundreds of them (also called nagma). Of course, sarangistudents are much in want by tablaplayers, who also have their extended repertoirs of lehra to match particular tala subdivisions etc.
Nowadays one can work with computerprograms and get many lehras in whatever sound, tala, speed etc etc. if you're in to all that HiTech Shiva stuff.