  We perform a resolvent analysis of a compressible turbulent jet, where the
optimisation domain of the response modes is located in the acoustic field,
excluding the hydrodynamic region, in order to promote acoustically efficient
modes. We examine the properties of the acoustic resolvent and assess its
potential for jet-noise modelling, focusing on the subsonic regime. Resolvent
forcing modes, consistent with previous studies, are found to contain
supersonic waves associated with Mach wave radiation in the response modes.
This differs from the standard resolvent in which hydrodynamic instabilities
dominate. We compare resolvent modes with SPOD modes educed from LES data.
Acoustic resolvent response modes generally have better alignment with acoustic
SPOD modes than standard resolvent response modes. For the optimal mode, the
angle of the acoustic beam is close to that found in SPOD modes for moderate
frequencies. However, there is no significant separation between the singular
values of the leading and sub-optimal modes. Some suboptimal modes are
furthermore shown to contain irrelevant structure for jet noise. Thus, even
though it contains essential acoustic features absent from the standard
resolvent approach, the SVD of the acoustic resolvent alone is insufficient to
educe a low-rank model for jet noise. But because it identifies the prevailing
mechanisms of jet noise, it provides valuable guidelines in the search of a
forcing model (Karban \textit{et al.} An empirical model of noise sources in
subsonic jets. \textit{Journal of Fluid Mechanics} (2023): A18).
