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 idealized 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 (Gottlieb 1977a:41). Furthermore the rhythmic concepts of the light and film musicians run at a higher tempo but show a peculiar compression of scale.

The tempo of the rhythm or the duration of pace or speed is called laya. It is regular spacing of time. Laya is three kinds: vilambit, madhya and drut.
Vilambit laya: Slow tempo of the rhythm is called vilambit lays. Each beat lasts for about one second. For example, dadra has six matras. Instead of counting six matras (beats) one after the other like 1, 2, 3, 4, 5, 6 vilambit laya will prolong it in the following manner.

Vilambit laya ---ISS --- ISS ---ISS ---ISS ---ISS ---ISS
Matra 1 2 3 4 5 6
+ (Tali) 0(Khali)
(S stands for prolongation of rhythm)
The following are some of the tals of vilambit lays: ektal, chartal, jhumra , tilwara.
Madhya laya: Medium tempo of the rhythm is called madhya laya. It can be compared to the ticking of about half second of the clock. Some of the tals of madhya lays are teental, jhaptal, dadra, kehrva.
Drut laya: is doubly quicker in tempo than the madhya laya. The tals of drut laya are the same as in madhya tal, the difference being that they are done quicker. Each beat lasts for about one-quarter second. Tarana and chota khayal use drut laya.

Other Kinds of Laya
There are other kinds of laya (tempo) in addition to vilambit, madhya, and drut laya mentioned. They give great joy to the listeners, especially in dhrupad, dhamar, and in instrumental music. These are as follows:
dugan (1/2), tigan (1/3), chaugan (1/4), aar (2/3), kunvaar (7/4), athagan (1/8)

Some of the layas which are popular are explained below:
Thhah Laya: In this laya, each anka takes one matra. It is also called Brabar Laya.
Dugan: In this laya there are two parts or anka in one matra:

1 2 3
1.2 3.4 5.6
Tigar: In this laya, there are three parts (anka) in one matra:

1 2 3 4
123 456 789 10 11 12
Chungan: In this laya, there are four parts (anka) in one matra:

1 2 3 4
1234 5678 9 10 11 12 13 14 15 16
Aar: In this laya, two matras are split into three matras. First the matras are divided into three parts and each is doubled up. “S” is used to complete the sequence:

1 S S 2 S S 3 S S 4 S S
Kunvaar: In this laya, five matras are split up into four parts. First the matras are divided into fourth parts and then grouped into five each.

1 S S S 2 S S S S 3 S S S 4 S S S 5 S S S
Beaar laya and athagam lays are not common and hence are omitted.

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

by David Courtney, Ph.D