About six years ago, finding that there was considerable difference of opinion as to what constituted D'Espine's sign, I looked up D'Espine's original descriptions of his "sign" and found them to be as follows:
In one article1 he said that he had called attention briefly to this method of diagnosis in 1889,2 and that Professor Brouardel, in a communication made for him at the session of the Academy of Nov. 8, 1904, said:
"The first signs of bronchial adenopathy are furnished exclusively by the auscultation of the voice, and are found almost always in the immediate neighborhood of the vertebral column between the seventh cervical vertebra and the first dorsal vertebra, sometimes in the fossa 'sus-épineuse,' sometimes in the interscapular space. They consist in a quality (timbre) added to the voice, which may be called whispering (chuchotement) in the first stage and bronchophony in a more advanced stage."
MORSE JL. D'ESPINE'S AND ALLIED SIGNS IN CHILDHOOD. Am J Dis Child. 1922;24(5):361-367. doi:10.1001/archpedi.1922.04120110002001