Arduino pseudocode:

# Define the pins for each sensor.
# Define the pin for the buzzer.
# Define the frequencies of the notes to be played by the buzzer.
# Define the distance range from the sensor.

Fetch distance from the first sensor.
If out of the defined range, skip to second sensor.
Else:
Go through the ranges, find in what range the distance falls.
Play the range's corresponding note on the buzzer. 
Delay.

Move on to fetch distance from second sensor. 
If out of the defined range, skip to third sensor.
Else:
Go through the ranges, find in what range the distance falls.Play the range's corresponding note on the buzzer.
Delay.

Move on to fetch distance from second sensor. If out of the defined range, loop back to first.
Else:
Go through the ranges, find in what range the distance falls.Play the range's corresponding note on the buzzer.
Delay.

Loop back to first sensor.