Lay is the tempo, or speed of a piece. The Hindi term for tempo is "lay" and is derived from the Sanskrit term "laya". It is a very simple concept, but its application is sometimes complicated.
It goes without saying that there have to be some practical limit to usable tempi. One beat every ten minutes would be so slow as to be musically useless. At the other end of the spectrum we can see that 100 beats per second would be so fast that it would be perceived as a tone and not as a rhythm. A general breakdown of Indian lay is shown in the following table:
The table is an idealised breakdown of lay; however, the real world is considerably more complex. For example the designations of ati drut, ati vilambit, etc. are seldom heard among practicing musicians. This tends to stretch the previous table so that there is no longer a 2-1 relationship between the various designations. To make matters even more complex, it has been observed that vocalists use a slower definition of time than instrumentalists. Furthermore the rhythmic concepts of the light and film musicians run at a higher tempo but show a peculiar compression of scale.
The lay or tempo usually changes throughout the performance. These changes in tempo are inextricably linked to the various musical styles. In general we can say that only very short pieces will maintain a fairly steady pace. Most styles will start at one tempo and then increase in speed.
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