In the world of diagnostics, we are currently moving away from using the label "Auditory Processing Disorder" as the research supports the idea that the characteristics of APD are just subsets of other disorders. Language, cognition, and physiological measures are all impacted. The children in the studies with suspected APD “scored lower on language and communication scales; experienced attention and memory difficulties; and achieved lower scores on tests of NV-IQ, language, and reading.” So, if your child has received a diagnosis of APD in the past, it is worth looking into the cognitive and language factors at play. It's not that the child isn't hearing the sounds, it is that the brain isn't interpreting those sounds correctly. Language intervention can be helpful - especially targeting phonological processing and short term memory skills - and help remediate the deficits. For more information, this large-scale review article examined almost 50 research studies to give a general consensus that APD is not a distinct clinical disorder:
de Wit, E., Visser-Bochane, M.I., Steenbergen, B., van Dijk, P., van der Schans, C.P., & Luinge, M.R. (2016). Characteristics of Auditory Processing Disorders: A Systematic Review. Journal of Speech, Language, and Hearing Research, 59, 384–413.