In turn, fine crackles are not confused so often with rhonchi and medium and coarse crackles, but are often confused with the crepitus category, which is a class that is much more often marked than that described by the standard (fine crackles). This is a situation that seems natural, because in the Polish medical community crepitus is equivalent to fine crackles, or is a subgroup for this class (Szczeklik, 1979). In the case of crepitus, the most common category marked was normal lung sound, which may mean that the respondents did not notice the sound class and treated the extra sound as an artifact occurring during the recording. This is confirmed by Fig. 10b, in which the answers other than those from the standard are shown for the normal lung sound, which was the correct (standard) response. It can be seen that the respondents, in addition to the correct answer, most often marked louder breath sound and crepitus. In the case of normal bronchial sound (Fig. 9a), the louder breath sound was more frequent than the standard one. In addition, the respondents also often noted a prolonged expiration phase.
In the samples that had louder breath sound (Fig. 9c), the subjects often recognized the respiratory pathology classes - inspiratory and expiratory wheezes or rhonchi. In the case of normal sounds, the selection of these classes was not observed.