A computer-implemented method comprises: (A) receiving first acoustic data representing a first cough train of a first human subject, wherein the first cough train comprises at least one first cough of the first human subject； (B) identifying at least one first value of at one first acoustic property of the first acoustic data； and (C) determining, based on the at least one first value of the at least one first acoustic property, whether the first acoustic data indicates that the first human subject has a severe respiratory illness.
