Explain how to use trills and shakes on a harmonica for adding expressive elements in blues playing, and demonstrate the proper execution of these techniques.

Trills and shakes are essential techniques for blues harmonica players, adding expressive and rhythmic variations to their playing. These techniques involve rapidly alternating between two notes, creating a shimmering or pulsating effect. While both trills and shakes involve rapid note alternation, their mechanics, sound, and applications in blues music are slightly different.

A trill is a rapid alternation between two notes that are close together in pitch, usually a half or whole step apart. The primary mechanism for creating a trill on the harmonica involves rapidly moving the tongue or the mouth, or a combination of both. For instance, to trill between two adjacent holes (for example, the 2 draw and the 3 draw on a C harmonica in second position), the player might use their tongue to rapidly alternate between the holes while keeping the breath steady. Another approach involves slightly moving the whole harmonica back and forth while keeping the mouth still, which makes the airflow change slightly between the two holes that you want to trill. The resulting sound is a fast, clear and distinct alternation between the two notes. Trills are often used to ornament a melody, or add a rhythmic texture and to create a more flowing sound. A good example of the use of trills, is when a player will trill quickly between the root note and a flat third, during a solo. This can add some bluesy flavor to the solo and create a very dynamic sound. You will often see this in many blues solos.

A shake, also known as a flutter, is a more rapid and less defined alternation between notes, often encompassing a wider interval than a trill. The main way of creating a shake on the harmonica is by using rapid movements of the diaphragm and mouth. This can be achieved by quickly varying the airflow, causing the note to rapidly oscillate in pitch without clearly articulating each note individually. For example, when playing a shake on a draw note, the player will quickly and rapidly change their diaphragm by breathing in and out very quickly. This will cause the note to quickly go up and down in pitch, creating a flutter effect. The player will also be moving their mouth and tongue back and forth to accentuate this flutter. Shakes typically create a more chaotic, vibrant, or tremolo-like effect compared to the more defined articulation of a trill. They are often used to add intensity and emotion to a performance. A good example of how shakes are used in blues is when a player will shake a note to add a more raw and emotional effect. The shake is not intended to be as precise and controlled as the trill but is more intended to create an unstable, moving and emotional sound. The player might hold a specific note, and then give it a shake to really add emphasis to the note and to express a certain emotion.

Both trills and shakes require good breath control. When performing a trill, the player needs to maintain a steady airflow, while when performing a shake the player will have to control their airflow, so it's fast and rapid, but also consistent. The control of the tongue and the mouth is also very important for the quality of these techniques. The choice between using a trill or a shake depends on the musical context. Trills are used for adding ornamentation to melodies, and shakes are used to create a more dramatic and raw expression. A skilled harmonica player will often alternate between both trills and shakes to add variation to their playing.

In summary, both trills and shakes are important techniques that harmonica players use for expression. Trills are more controlled and use distinct, rapidly alternating notes, while shakes are less controlled and often use rapid, less clearly articulated oscillations in pitch. Both add to the texture and expression of the blues harmonica sound.