Abstract: Intracranial aneurysms generate aneurysm-characteristic sounds which emanate externally from the head, are monitored, and are then analyzed to produce information indicative of the probable existence of the aneurysm. The method is non-invasive, does not require hospitalization, and is repeatedly used to diagnose probable aneurysm presence and the onset and continuation of spasm. Information from repeated samplings aids in following and diagnosing patient status pre-bleed, during bleed, post-bleed and pre- and post-operative.