Dominant Extensions, Scales, and Wind Instrumentation

Dominant extensions are highly flexible compared to major or minor chords, allowing for notes to be altered up or down by a semi-tone.
Standard dominant chords contain four chord tones; however, the $5$ is frequently omitted in real-world voicings.
Unaltered extensions are typically used in major keys, while altered extensions are more common in minor keys.
Functionally, dominant chords serve two main roles: traditional dominant-tonic resolution or as a temporary tonic (arrival point).

$9$ Chords: The unaltered $M9$ is used in funk or jazz as a tonic sound. The $b9$ is used to resolve to minor chords. The $\#9$ is often expressed as a $b10$ (essentially a $b3$ voiced a $M7$ above the $M3$ ).
$11$ Chords: Generally used as a raised $\#11$ . It is less common than $9$ or $13$ extensions and often requires omitting the $5$ .
$13$ Chords: The $11$ is usually omitted. While $\#11$ can be added, it is rare. The $13$ can be flatted ( $b13$ ), which requires omitting the $5$ . A $b13$ is typically used in transition chords, not as a tonic.
Altered (Alt) Chords: A blanket term for chords containing both an altered $9$ and an altered $13$ . The most common commercial combination is $\#9/b13$ .

Minor Scales:
- Natural: Based on the $6^{th}$ scale degree of the major scale.
- Harmonic: Natural minor with a raised $7^{th}$ .
- Melodic: Harmonic minor with a raised $6^{th}$ .
Diatonic Modes: Derived by starting a Major scale on different degrees:
- Ionian: $1^{st}$ degree (Major).
- Dorian: $2^{nd}$ degree (Natural minor with a raised $6^{th}$ ).
- Lydian: $4^{th}$ degree (Major with a raised $4^{th}$ , used for "cinematic" $\#11$ sounds).
- Mixolydian: $5^{th}$ degree (Major with a lowered $7^{th}$ , useful for dominant chords).
- Aeolian: $6^{th}$ degree (Natural minor).
- Phrygian and Locrian: Other standard diatonic modes.
Pentatonics: Includes Major, minor, and Blues scales; particularly effective when the melody does not need to strictly outline every chord change.

Pentatonic scales can be superimposed over complex chords to simplify melody creation.
$9^{th}$ Chords: Use a pentatonic scale starting a $5^{th}$ above the root (e.g., $C9$ uses $G$ major or minor pentatonic).
Major $\#11$ Chords: Use a major pentatonic scale starting two $5^{th}s$ ( $M2$ ) above the root (e.g., $C\text{maj}7(\#11)$ uses $D$ major pentatonic).
Minor $13$ Chords: Use a minor pentatonic scale starting two $5^{th}s$ ( $M2$ ) above the root (e.g., $C$ uses $D$ minor pentatonic).

Flute: The only non-reed transverse woodwind. Registers vary from breathy/weak (low) to singing/bright (middle) to piercing/shrill (high).
Oboe: A double-reed instrument made of wood. Known for a reedy, poignant, and thick timbre; players typically make their own reeds.
Clarinet: A single-reed instrument. Registers include the deep "Chalumeau," the pale "Throat tones," and the bright, expressive "Clarino."
Bassoon: A double-reed instrument providing the low end of the woodwind section; often doubles the cellos.
Saxophones: Available primarily as Soprano, Alto, Tenor, and Baritone.

French Horn (Horn in F): Features a valve system. It is bright and heroic in the upper-mid range but becomes unfocused in the lowest register. Players usually prefer staying below written $G5$ .
Trumpet: Highly versatile and agile, capable of fast chromatic passages. Timbre ranges from dull (low) to brilliant/strident (high).
Trombone: Uses a slide system, making slurring more difficult compared to valved instruments. Includes the Tenor and the powerful, heavy Bass Trombone.
Tuba: Provides the heavy foundation for the brass section. It is less agile and has a limited range due to extreme breath requirements.