Sound files need to be placed here by the developer.

Required OGG files in assets/echo_gates/sounds/:
- portal_ambient.ogg    (looping deep resonant hum - use sculk sensor ambient as base)
- heartbeat_near.ogg    (warden heartbeat thump - use warden.heartbeat as base)  
- portal_activate.ogg   (large resonant boom with sculk tones)
- portal_travel.ogg     (whooshing tunnel effect)
- portal_arrive.ogg     (resonant arrival chime)

Free/libre sound suggestions:
- Portal ambient: Combine Minecraft's ambient.sculk_sensor with a low drone
- Heartbeat: Use minecraft:entity.warden.heartbeat directly in sounds.json
- Activate: Use minecraft:block.beacon.activate + entity.warden.emerge blend
- Travel: Use minecraft:block.nether_portal.travel as a base, shift pitch down
- Arrive: Use minecraft:block.sculk.charge reversed

You can reference Minecraft's built-in sounds in sounds.json using "minecraft:" prefix.
See the sounds.json implementation that uses "sounds" array entries.
