How did blues musicians use blue notes to express emotion?

In the context of blues music, musicians use blue notes to express raw emotion, particularly feelings of sadness, melancholy, or the hardships of life.12

Blue notes are characterized as expressive, microtonal pitch inflections—specifically the variable lowering of the third, seventh, and occasionally the fifth degrees of a major scale. By utilizing these flatted or "bent" notes, performers create a plaintive, mournful, or "whining" sound that mimics the nuances of human speech and lamentation.1324

In the Mississippi Delta blues tradition, this emotional expression is further enhanced by instrumental techniques such as "choking" or bending guitar strings, or by using a metal slide or bottleneck along the fingerboard to achieve these microtonal shifts. These techniques allow the instrument to "talk" or "speak," effectively mirroring the vocal idioms used by blues singers to convey their personal and collective experiences of oppression and struggle.152