  Let $p$ be an odd prime number, and let $E$ be an elliptic curve defined over
a number field $F'$ such that $E$ has semistable reduction at every prime of
$F'$ above $p$ and is supersingular at at least one prime above $p$. Under
appropriate hypotheses, we compute the Akashi series of the signed Selmer
groups of $E$ over a $\mathbb{Z}_p^d$-extension over a finite extension $F$ of
$F'$. As a by-product, we also compute the Euler characteristics of these
Selmer groups.
