Can you hear with only brain stem activity?

Yes, it is possible to hear with only brainstem activity. The brainstem is the lowest part of the brain and it contains the auditory brainstem nuclei, which are responsible for processing sound information. In cases where the higher parts of the brain are damaged or disconnected from the brainstem, people can still hear and process sounds, although their ability to understand and interpret them may be impaired. This phenomenon is known as "locked-in syndrome" or "pseudocoma," and it demonstrates the remarkable ability of the brainstem to support basic auditory functions even in the absence of higher-level cognitive processing.