A system includes an in-ear acoustic device that is configured to sit at least partially within a user's ear canal and a head-worn electronic device that is supported on a user's body outside of the user's ear canal. The in-ear acoustic device includes a first receiver and a first coil. The head-worn electronic device includes a second coil that is configured to communicate with the first coil via near-field magnetic inductance (NFMI) communication. The head-worn electronic device is configured to transmit a first processed audio signal to the in-ear acoustic device via NFMI communication, and the first processed audio signal is used to drive the first receiver.