Ann: Preliminary Top-line Results from SMARTCOUGH-C Study, page-171

"The following table shows the positive percent agreement (PPA) and negative percent
agreement (NPA) with clinical diagnosis and the corresponding 95% confidence intervals
for each endpoint. Patients which were identified as having obvious background noise
have been excluded from this analysis. The final number of croup patients, after
removing those who were treated prior to cough recording, did not allow for a
statistically meaningful analysis."

Looks like it's over to me. These results already exclude obvious background noise, and they already removed those who were treated prior to cough recording, at least for the croup patients.