Final answer:
The four most common brass instruments in the traditional symphony orchestra are the trumpet, french horn, trombone, and tuba.
Step-by-step explanation:
The four most common brass instruments in the traditional symphony orchestra are the trumpet, french horn, trombone, and tuba. These instruments are part of the brass family and are typically made of brass alloys, which are strong and durable. Each instrument has a unique sound and range, and they all play an important role in the orchestra.