Heart and Lung Sounds Reference Guide Aortic Pulmonic Erb's Point Tricuspid Mitral Lungs Crackles - Late Inspiratory (Rales) Auscultation Reference Signup Now. Unlock lessons and more. SignUp Patient Normal Speed play pause Patient Half Speed play pause Lesson For heart sounds listen to the synthetic sound while reviewing this lesson. Late inspiratory crackles (rales) begin in late inspiration and increase in intensity. They are normally higher pitched and can vary in loudness. These adventitious breath sounds resemble the noise made when hook and loop fasteners are being separated. These sounds are heard over posterior bases of the lungs. They may clear with changes in posture or several deep breaths. They do not clear with coughing. The waveform(s) seen above are a chart of sound amplitude (loudness) on the vertical axis against time on the horizontal axis. Listening Tips A summary of the key aspects of this heart or lung sound. Crackles begin in late inspiration and increase. High pitched, variable loudness. Best heard over posterior bases of the lungs. Do not usually clear with coughing. Auscultation Method The recommended patient position is sitting For this sound, use stethoscope's diaphragm The recommended auscultation position for the stethoscope is posterior-3l Relevant Courses If you wish to review a complete mobile concerning Crackles - Late Inspiratory (Rales) Auscultation Reference and related heart sounds, the modules(s) listed below may be useful. Each lesson includes text that explains the auscultatory sound and its clinical significance. The lesson also includes an audio track for playback. A waveform provides a great way to visualize the sounds. Finally, we also include an animation video. For heart sounds, the video illustrates heart muscle and valve movements along with blood flow. For lung sounds, the primary source of the sounds can be seen. Each module also includes a quiz. Intermediate Lung Sounds202 Crackles - Late Inspiratory (Rales) Auscultation Reference