Biome Music breaking my Minecraft world

I'm trying to add custom music to this biome, but when I try to join the world with it, Minecraft doesn't let me, because it can't find the sound file I specified.  I don't know how to fix this...
The sound files are:
assets/sbm1/sounds.json
assets/sbm1/sounds/ambient_music.ogg
    "temperature": 0.8,
    "downfall": 0.4,
    "has_precipitation": true,
    "effects": {
        "sky_color": 0,
        "fog_color": 0,
        "water_color": 5303807,
        "water_fog_color": 5303807,
        "grass_color": 5620055,
        "foliage_color": 1879583,
        "music": [
            {
                "data": {
                    "sound": "sbm:ambient_music",
                    "max_delay": 0,
                    "min_delay": 1,
                    "replace_current_music": true
                },
                "weight": 1
            }
        ]
    },
    "spawners": {},
    "spawn_costs": {},
    "carvers": [],
    "features": []
}```