Measurements of the times of flight of sound waves can be used to determine temperature in a gas contained in a long tube which confines sound waves. Sound pulses are transmitted and received by a suitable loud speaker attached to one end of the long tube. A number of stubs or other discontinuities produce...http://www.google.com/patents/US4762425?utm_source=gb-gplus-sharePatent US4762425 - System for temperature profile measurement in large furnances and kilns and method therefor
