An experiment was designed to identify the voice change as a specific structural feature of radio that causes automatic allocation of cognitive resources to message encoding. The cardiac orienting response (OR) was used as an indication of this automatic resource allocation. It was hypothesized that listeners would exhibit cardiac ORs in response to voice changes and that the associated automatic resource allocation would result in momentary cognitive overload. Data were collected from 62 participants as they listened to nine messages that varied in the number of voice changes they contained. Results show robust cardiac orienting to voice changes and suggest that this response does not habituate over the course of 2-minute messages. Furthermore, auditory recognition data show that not only does orienting to voice changes result in momentary cognitive overload, but the severity of that overload depends on the total number of voice changes in the message.