1. Playing with different dynamics. The harder you play, the louder the instrument will sound. The softer you play, the quieter the instrument will sound.
2. Changing the position of your instrument. Playing closer to the bridge will create a louder sound. Playing further from the bridge will create a mellower sound.
3. Using different fingering techniques. The use of vibrato can create a louder, more resonant sound. Using staccato and other articulation techniques can create a quieter, more defined sound.
4. Using different instruments. Instruments have different natural volumes. A brass instrument is generally louder than a string instrument.
5. Using amplifiers and effects pedals. Amplifiers and effects pedals can be used to make an instrument louder, or to change the overall tone of the instrument.
By adjusting these factors, you can control the loudness of an instrument to create the desired sound.