Acoustic pulse reflectometry for the measurement of horn crooks

The echo-based technique of acoustic pulse reflectometry can be used to measure tubular objects to determine the bore profile. In this paper, measurements of historic orchestral crooks are presented showing how the technique ca help to determine the method of construction of historic crooks and can provide valuable information to manufacturers of reproduction period instruments. Comparison of the bore profile measured by pulse reflectometry and the know exit radius of the crook can be used to determine the presence of leaks. The technique is shown to be sensitive enough to find a leak in a horn crook that behaves reasonable under playing conditions and was not suspected of having a leak prior to testing.