The sam or sum [pronounced sum] is always the first matra of an avartan. For example, in teentaal, the first matra, Ta, is the sam.
The sam is usually stressed when playing and is particularly important when playing in groups. During a performance, one musician provides a steady rhythm by playing theka, while the other improvises. When it is time to switch roles, the two musicians can easily coordinate by using the sam as a marker, since it is the beginning of the next avartan.