diff --git a/player/ring.py b/player/ring.py
index 88cdf51..4fbecbe 100644
--- a/player/ring.py
+++ b/player/ring.py
@@ -63,6 +63,7 @@ class Scale:
     id: str
     clip_id: str
     pool: tuple[str, ...] = ()
+    audio: str = ""              # per-scale soundtrack, relative to /media/audio/ (audio spec §5.1)
 
     @property
     def members(self) -> tuple[str, ...]:
diff --git a/simulator/build_pool_manifest.py b/simulator/build_pool_manifest.py
index ef3d35d..38148d7 100644
--- a/simulator/build_pool_manifest.py
+++ b/simulator/build_pool_manifest.py
@@ -48,6 +48,16 @@ POOLS: dict[str, list[str]] = {
 # Ring order (large -> small, wraps): cosmos -> orbit -> coast -> reef -> abyss -> cosmos.
 RING_ORDER = ["cosmos", "orbit", "coast", "reef", "abyss"]
 
+# Per-scale soundtrack (audio spec §5.1) — the production-pass output of
+# simulator/build_audio_media.py, served at /media/audio/<path>.
+SCALE_AUDIO: dict[str, str] = {
+    "cosmos": "cosmos/pillars.loop.mp3",
+    "orbit": "orbit/spaceamb.loop.mp3",
+    "coast": "coast/waves.loop.mp3",
+    "reef": "reef/soundscape.loop.mp3",
+    "abyss": "abyss/whale.loop.mp3",
+}
+
 PD = "public-domain (US Gov, 17 U.S.C. §105)"
 PD_NPS = "public-domain (NPS, no © — 17 U.S.C. §105)"
 CCBY_STSCI = "CC-BY-class — credit NASA, ESA, STScI"
@@ -357,7 +367,10 @@ def build_manifest() -> dict:
     for scale in RING_ORDER:
         for clip_id in POOLS[scale]:
             clips.append(_clip_entry(scale, clip_id))
-    scales = [{"id": s, "clip_id": POOLS[s][0], "pool": POOLS[s]} for s in RING_ORDER]
+    scales = [
+        {"id": s, "clip_id": POOLS[s][0], "pool": POOLS[s], "audio": SCALE_AUDIO[s]}
+        for s in RING_ORDER
+    ]
     transitions = []
     n = len(RING_ORDER)
     for i in range(n):
diff --git a/simulator/clips.py b/simulator/clips.py
index 00d2b49..33b2db1 100644
--- a/simulator/clips.py
+++ b/simulator/clips.py
@@ -82,7 +82,7 @@ def _scale_from_dict(s: dict[str, Any]) -> Scale:
     """
     pool = tuple(s.get("pool", []))
     clip_id = s.get("clip_id") or (pool[0] if pool else "")
-    return Scale(id=s["id"], clip_id=clip_id, pool=pool)
+    return Scale(id=s["id"], clip_id=clip_id, pool=pool, audio=s.get("audio", ""))
 
 
 def load_ring(path: str | Path) -> ScaleRing | None:
@@ -119,6 +119,7 @@ def ring_to_dict(ring: ScaleRing, clips: list[Clip]) -> dict:
                 "id": s.id,
                 "clip_id": s.clip_id,
                 "title": titles.get(s.clip_id, s.id),
+                "audio": s.audio,
                 "pool": [
                     {"clip_id": cid, "title": titles.get(cid, cid)}
                     for cid in s.members
diff --git a/simulator/sample_media/manifest.json b/simulator/sample_media/manifest.json
index bf62d17..24a8c13 100644
--- a/simulator/sample_media/manifest.json
+++ b/simulator/sample_media/manifest.json
@@ -2371,7 +2371,8 @@
           "cosmos_galaxies",
           "cosmos_hudf",
           "cosmos_xdf"
-        ]
+        ],
+        "audio": "cosmos/pillars.loop.mp3"
       },
       {
         "id": "orbit",
@@ -2380,7 +2381,8 @@
           "orbit_planetearth",
           "orbit_crewobs",
           "orbit_bluemarble"
-        ]
+        ],
+        "audio": "orbit/spaceamb.loop.mp3"
       },
       {
         "id": "coast",
@@ -2390,7 +2392,8 @@
           "coast_surfgrass",
           "coast_elkbeach",
           "coast_drakesbeach"
-        ]
+        ],
+        "audio": "coast/waves.loop.mp3"
       },
       {
         "id": "reef",
@@ -2401,7 +2404,8 @@
           "reef_hawkfish",
           "reef_snapper",
           "reef_coralspacific"
-        ]
+        ],
+        "audio": "reef/soundscape.loop.mp3"
       },
       {
         "id": "abyss",
@@ -2410,7 +2414,8 @@
           "abyss_wow",
           "abyss_midwaterexp",
           "abyss_hiding"
-        ]
+        ],
+        "audio": "abyss/whale.loop.mp3"
       }
     ],
     "transitions": [
diff --git a/tests/test_player_ring.py b/tests/test_player_ring.py
index ddb1a87..4841234 100644
--- a/tests/test_player_ring.py
+++ b/tests/test_player_ring.py
@@ -240,3 +240,10 @@ def test_pick_clip_id_clamps_out_of_range_r():
     assert pick_clip_id(s, -5.0) == "a"      # below 0 clamps to first
     assert pick_clip_id(s, 1.0) == "c"        # 1.0 must not index past the end
     assert pick_clip_id(s, 999.0) == "c"
+
+
+def test_scale_carries_an_optional_audio_path():
+    s = Scale(id="coast", clip_id="coast_birdrock", audio="coast/waves.loop.mp3")
+    assert s.audio == "coast/waves.loop.mp3"
+    # back-compat: audio defaults to empty
+    assert Scale(id="x", clip_id="x").audio == ""
diff --git a/tests/test_simulator_api.py b/tests/test_simulator_api.py
index 0e39a70..94f7330 100644
--- a/tests/test_simulator_api.py
+++ b/tests/test_simulator_api.py
@@ -162,9 +162,9 @@ def ring_manifest_path(tmp_path):
         ],
         "ring": {
             "scales": [
-                {"id": "cosmos", "clip_id": "cosmos"},
-                {"id": "forest", "clip_id": "forest"},
-                {"id": "abyss", "clip_id": "abyss"},
+                {"id": "cosmos", "clip_id": "cosmos", "audio": "cosmos/pillars.loop.mp3"},
+                {"id": "forest", "clip_id": "forest", "audio": "forest/amb.loop.mp3"},
+                {"id": "abyss", "clip_id": "abyss", "audio": "abyss/whale.loop.mp3"},
             ],
             "transitions": [
                 {"file": "transitions/cosmos-forest.mp4", "model": "placeholder"},
@@ -190,6 +190,15 @@ def test_ring_returns_scales_and_transitions(ring_client):
     assert len(data["transitions"]) == 3
 
 
+def test_ring_exposes_each_scales_audio(ring_client):
+    body = ring_client.get("/api/ring").json()
+    by_id = {s["id"]: s for s in body["scales"]}
+    # every scale advertises its soundtrack path (audio spec §5.1)
+    assert by_id["cosmos"]["audio"] == "cosmos/pillars.loop.mp3"
+    assert by_id["abyss"]["audio"].endswith(".mp3")
+    assert "audio" in by_id["forest"]
+
+
 def test_ring_advance_inward_one_step(ring_client):
     resp = ring_client.post("/api/ring/advance", json={"from_index": 0, "delta": 1})
     assert resp.status_code == 200