  In this paper we study relations between the \emph{left-right-measure} and
properties of singular masas. Part of the analysis is mainly concerned with
masas for which the \emph{left-right-measure} is the class of product measure.
We provide examples of Tauer masas in the hyperfinite $\rm{II}_{1}$ factor
whose \emph{left-right-measure} is the class of Lebesgue measure. We show that
for each subset $S\subseteq \mathbb{N}$, there exist uncountably many pairwise
non conjugate singular masas in the free group factors with \emph{Puk\'{a}nszky
invariant} $S\cup\{\infty\}$.
