Things that produce sounds vary. Everyday objects can produce a sound. It can vary in volume and pitch. If the person has a favorite instrument see if a relative will bring it in if it is portable. Find recordings of their favorite familiar music. Keep beats and rhythms simple. Other sounds that capture attention are things like bike bells.
Their recognition of loved ones and consistent caregivers is difficult to be objective about. When frequent startle reactions or pain have been stimulated, agitation when any caregiver approaches their bedside usually occurs. The color that the person was wearing might be the cue that triggers agitation. Recognizing the face and voice of a loved one may not get a better arousal of attention in ACL 1 Low. Responding to the face and sound of loved ones usually goes before responding to the call of their name within ACL 1.4.
The person can respond to simple speech like their name being called in ACL 1.4.