Copy these lines into your sound.txt located in the data/sound dir:

9701				// Sound ID
0x00,0x01			// Type (0), Flags (0)
eclipse.WAV		// File name
7000				// Priority
1					// Repeat rate
250,250 			// MinVol, MaxVol
0,1					// MinPitch, MaxPitch
0,1					// MinSpeed, MaxSpeed
0x0					// Special FX index
0					// Number of low memory alternatives
