The sound barrier.
Strachan
J
J
D003144:Communication Barriers; D003638:Deafness / Q000523:psychology*; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008085:Lipreading; D010817:Physician-Patient Relations; D010821:Physicians, Family / Q000193:education / Q000523:psychology; D012813:Sign Language