In Colin Cherry's experiment, participants commonly failed to do two things: they did not notice when the language of the conversation switched from English to another language, and they were often unaware of the meaning of the message being presented in the unattended channel.
On the other hand, participants were able to detect two specific elements regarding the information they rejected or did not attend to: they could discern changes in the speaker's voice or tone, and they were aware of whether the unattended message contained a repetitive or familiar sound, such as their own name being mentioned. This supported Cherry's claim that our attention is selective, and we absorb very little information from conversations we do not focus on.