Atelectasis Clinical Presentation. ... over the involved area and diminished or absent breath sounds. Auscultation of lungs, main respiratory sounds (bronchial and vesicular breathing). ... demonstrate dullness to percussion over the involved area and diminished or absent breath sounds. In left lower lobe (LLL) ... Atelectasis. Bibasal or bibasilar crackles refer to crackles at the bases of both the left and ... Coarse crackles are somewhat louder, lower in ... - sound files of breath sounds