  In this paper, we study the behaviour of the coupled subwavelength resonant
modes when two high-contrast acoustic resonators are brought close together. We
consider the case of spherical resonators and use bispherical coordinates to
derive explicit representations for the capacitance coefficients which, we
show, capture the system's resonant behaviour at leading order. We prove that
the pair of resonators has two subwavelength resonant modes whose frequencies
have different leading-order asymptotic behaviour. We, also, derive estimates
for the rate at which the gradient of the scattered pressure wave blows up as
the resonators are brought together.
