A wheeze (formally called sibilant rhonchi in medical terminology) is a continuous, coarse, whistling sound produced in the respiratory airways during breathing.For wheezes to occur, some part of the respiratory tree must be narrowed or obstructed, or airflow velocity within the respiratory tree must be heightened. wheeze (formally called sibilant rhonchi in medical terminology) is a continuous, coarse, whistling sound produced in the respiratory airways during breathing.