  There is event by event geometric as well as quantum fluctuations in the
initial condition of heavy-ion collisions. The standard technique of analysing
heavy-ion collisions in bins of centrality obtained from final state
multiplicity averages out the various initial configurations and thus restricts
the study to only a limited range of initial conditions. In this paper, we
propose an additional binning in terms of total spectator neutrons in an event.
This offers us a key control parameter to probe events with broader range of
initial conditions providing us an opportunity to peep into events with rarer
initial conditions which otherwise get masked when analysed by centrality
binning alone. We find that the inclusion of spectator binning allows one to
vary $\varepsilon_2$ and $\varepsilon_3$ independently. We observe that the
standard scaling relation between $\displaystyle{v_2/\varepsilon_2}$ and
$\frac{1}{S}\frac{dN_{\text{ch}}}{d\eta}$ exhibited by centrality bins is
broken by the spectator neutron bins. However, the acoustic scaling relation
between $\displaystyle{\ln\left( v_n/\varepsilon_n\right)}$ and transverse
system size holds for both centrality as well as spectator bins for central to
mid-central collisions. The introduction of the spectator binning allows us to
tune over a wide range viscosity driven effects for events with varying initial
states but similar final state multiplicity.
