Refinement steps buy intelligibility, not identity — measured
Per-metric (width, depth,
steps) scaling for masked-diffusion TTS.
Every number on this page comes from results/artifacts/runs.csv,
results/artifacts/fits.json or results/artifacts/c_layer.json.
Declared outcome class: S1 — test-time scaling is metric-selective — refinement steps buy intelligibility far faster than speaker identity.
§1What was run
| Item | Value |
|---|---|
| Training data | 2000 h Emilia-EN, 792,064 clips, 64,680 speakers (≥4,000 required), 200 held-out speakers |
| sec_per_char (Phase 0, median over 10,000 clips) | 0.06020 |
| Recipe | coarse-to-fine (grid.json backbone.training_objective) |
| T semantics | steps per level, NFE = 8T (grid.json sampler_frozen.T_definition) |
| μP base LR (chosen at G1) | 0.004 |
| Completed runs | 45 |
| Compute used | 142.9 / 500 B200-h |
| SIM-o model | wavlm_large_sv_unispeech(seed-tts-eval) |
| Eval-harness sanity (G0c, ground-truth audio) | WER 3.4% · same-speaker SIM 0.701 · cross-speaker SIM 0.034 |
§2The step axis (Part B — primary)
| Metric | α (width) | β (depth) | τ (steps) | τ 95% CI | κ | κ 95% CI | ΔAICc(sub−sep) | ΔAICc(full−N) |
|---|---|---|---|---|---|---|---|---|
| WER | 1.574 | 2.040 | 0.836 | [0.825, 0.851] | 3.000 | [3.000, 3.000] | 69.3 | -15.5 |
| SIM-o | 0.919 | 0.553 | 0.726 | [0.709, 0.744] | 3.000 | [3.000, 3.000] | 71.3 | -5.5 |
Δτ = 0.110, 95% CI [0.092, 0.131] — excludes 0. Bootstrap: run-level, 2000/2000 replicates converged, RNG 7331. Saturation steps, normalised to each metric's own total T-gain (affine-invariant): T* = 16 for both WER and SIM-o. The raw-scale variant of this statistic (WER 16, SIM-o 8) is withdrawn — the 5% band is 0.67% of WER's range but 11.96% of SIM's, a 17.9× difference in strictness, so the apparent gap was an artifact of scale and not of the models' behaviour.
§3Anisotropy at T=16 (Part A — secondary)
| Metric | α | β | ρ=α/β | E | ΔAICc(full−N) | shape matters (ΔAICc ≤ −4) |
|---|---|---|---|---|---|---|
| WER | 1.338 | 1.935 | 0.692 | 0.109 | -15.5 | yes |
| SIM-o | 0.893 | 1.031 | 0.866 | 0.565 | -5.5 | yes |
Δρ = ρSIM − ρWER = 0.174, CI [-0.711, 0.388]. H-D4 (extrapolation to the largest budget): WER MAPE 20.2% under M_full vs 20.4% under the N-only model; SIM-o 2.4% vs 2.2%.
§4Budget-constrained minima on the measured T ≤ 16 grid
Serial latency per utterance = 8·T·d·c_layer(w) (grid.json latency_model) with
c_layer measured on NVIDIA B200 at batch 1:
w=256: 0.497 ms, w=320: 0.510 ms, w=384: 0.514 ms, w=448: 0.500 ms, w=512: 0.493 ms, w=640: 0.506 ms, w=768: 0.498 ms, w=832: 0.499 ms, w=960: 0.493 ms, w=1152: 0.502 ms.
For each budget the table gives the (w, d, T) point of the measured grid that minimises the
fitted Msep prediction subject to the budget. Caveat: T is censored at the grid
maximum of 16, and every optimum at ≥ 1000 ms sits exactly on that boundary, so this table
supports no depth-versus-steps ordering — on the extended T ≤ 64 grid the ordering reverses.
No allocation rule is claimed here.
| Metric | Budget (ms) | Best config | w | d | T | latency (ms) | predicted err |
|---|---|---|---|---|---|---|---|
| WER | 200 | B1 | 832 | 6 | 8 | 192 | 0.3169 |
| WER | 500 | C2 | 960 | 12 | 8 | 379 | 0.2267 |
| WER | 1000 | C2 | 960 | 12 | 16 | 757 | 0.1398 |
| WER | 2000 | B5 | 384 | 30 | 16 | 1974 | 0.1159 |
| WER | 4000 | C5 | 512 | 36 | 16 | 2272 | 0.1142 |
| SIM | 200 | B1 | 832 | 6 | 8 | 192 | 0.6518 |
| SIM | 500 | C2 | 960 | 12 | 8 | 379 | 0.6299 |
| SIM | 1000 | C2 | 960 | 12 | 16 | 757 | 0.6133 |
| SIM | 2000 | C4 | 640 | 26 | 16 | 1684 | 0.6071 |
| SIM | 4000 | C4 | 640 | 26 | 16 | 1684 | 0.6071 |
§5Measured surface
| config | w | d | N | T | WER | SIM-o | DegenRate | UTMOS | val loss | latency (ms) |
|---|---|---|---|---|---|---|---|---|---|---|
| A1 | 640 | 4 | 19.7M | 1 | 112.8% | 0.198 | 39.3% | 1.52 | 4.6377 | 16 |
| A1 | 640 | 4 | 19.7M | 2 | 102.0% | 0.249 | 15.5% | 1.86 | 4.6377 | 32 |
| A1 | 640 | 4 | 19.7M | 4 | 77.6% | 0.289 | 3.8% | 2.32 | 4.6377 | 65 |
| A1 | 640 | 4 | 19.7M | 8 | 61.3% | 0.315 | 1.6% | 2.64 | 4.6377 | 130 |
| A1 | 640 | 4 | 19.7M | 16 | 53.9% | 0.327 | 0.7% | 2.84 | 4.6377 | 259 |
| A2 | 448 | 8 | 19.3M | 1 | 117.2% | 0.202 | 41.8% | 1.52 | 4.5818 | 32 |
| A2 | 448 | 8 | 19.3M | 2 | 86.5% | 0.267 | 11.0% | 1.90 | 4.5818 | 64 |
| A2 | 448 | 8 | 19.3M | 4 | 50.8% | 0.311 | 1.2% | 2.40 | 4.5818 | 128 |
| A2 | 448 | 8 | 19.3M | 8 | 34.7% | 0.338 | 0.3% | 2.72 | 4.5818 | 256 |
| A2 | 448 | 8 | 19.3M | 16 | 28.4% | 0.348 | 0.1% | 2.91 | 4.5818 | 512 |
| A3 | 384 | 12 | 21.2M | 1 | 113.9% | 0.202 | 40.8% | 1.52 | 4.5661 | 49 |
| A3 | 384 | 12 | 21.2M | 2 | 83.2% | 0.265 | 9.8% | 1.91 | 4.5661 | 99 |
| A3 | 384 | 12 | 21.2M | 4 | 34.6% | 0.319 | 1.1% | 2.45 | 4.5661 | 197 |
| A3 | 384 | 12 | 21.2M | 8 | 19.7% | 0.346 | 0.0% | 2.77 | 4.5661 | 395 |
| A3 | 384 | 12 | 21.2M | 16 | 15.9% | 0.360 | 0.2% | 2.96 | 4.5661 | 789 |
| A4 | 320 | 18 | 22.1M | 1 | 115.4% | 0.203 | 39.9% | 1.52 | 4.5740 | 74 |
| A4 | 320 | 18 | 22.1M | 2 | 77.1% | 0.266 | 7.8% | 1.93 | 4.5740 | 147 |
| A4 | 320 | 18 | 22.1M | 4 | 30.5% | 0.320 | 0.4% | 2.48 | 4.5740 | 294 |
| A4 | 320 | 18 | 22.1M | 8 | 17.8% | 0.347 | 0.0% | 2.79 | 4.5740 | 588 |
| A4 | 320 | 18 | 22.1M | 16 | 13.6% | 0.359 | 0.0% | 2.94 | 4.5740 | 1176 |
| A5 | 256 | 24 | 18.9M | 1 | 115.8% | 0.194 | 38.2% | 1.52 | 4.6112 | 95 |
| A5 | 256 | 24 | 18.9M | 2 | 76.2% | 0.260 | 9.5% | 1.91 | 4.6112 | 191 |
| A5 | 256 | 24 | 18.9M | 4 | 34.2% | 0.313 | 0.8% | 2.43 | 4.6112 | 382 |
| A5 | 256 | 24 | 18.9M | 8 | 20.8% | 0.339 | 0.2% | 2.76 | 4.6112 | 763 |
| A5 | 256 | 24 | 18.9M | 16 | 15.3% | 0.351 | 0.2% | 2.92 | 4.6112 | 1527 |
| B1 | 832 | 6 | 49.9M | 1 | 112.1% | 0.212 | 39.4% | 1.54 | 4.5506 | 24 |
| B1 | 832 | 6 | 49.9M | 2 | 85.1% | 0.269 | 9.4% | 1.93 | 4.5506 | 48 |
| B1 | 832 | 6 | 49.9M | 4 | 49.8% | 0.320 | 1.7% | 2.43 | 4.5506 | 96 |
| B1 | 832 | 6 | 49.9M | 8 | 33.7% | 0.345 | 0.4% | 2.75 | 4.5506 | 192 |
| B1 | 832 | 6 | 49.9M | 16 | 27.8% | 0.361 | 0.1% | 2.93 | 4.5506 | 383 |
| B2 | 640 | 10 | 49.2M | 1 | 113.9% | 0.208 | 43.2% | 1.51 | 4.5049 | 40 |
| B2 | 640 | 10 | 49.2M | 2 | 76.6% | 0.282 | 9.0% | 1.94 | 4.5049 | 81 |
| B2 | 640 | 10 | 49.2M | 4 | 33.6% | 0.341 | 0.2% | 2.48 | 4.5049 | 162 |
| B2 | 640 | 10 | 49.2M | 8 | 20.9% | 0.371 | 0.2% | 2.81 | 4.5049 | 324 |
| B2 | 640 | 10 | 49.2M | 16 | 16.0% | 0.381 | 0.0% | 2.98 | 4.5049 | 648 |
| B3 | 512 | 16 | 50.3M | 1 | 114.9% | 0.212 | 40.3% | 1.52 | 4.4971 | 63 |
| B3 | 512 | 16 | 50.3M | 2 | 72.9% | 0.293 | 7.5% | 1.96 | 4.4971 | 126 |
| B3 | 512 | 16 | 50.3M | 4 | 26.8% | 0.347 | 0.3% | 2.53 | 4.4971 | 252 |
| B3 | 512 | 16 | 50.3M | 8 | 16.6% | 0.376 | 0.0% | 2.83 | 4.4971 | 505 |
| B3 | 512 | 16 | 50.3M | 16 | 11.9% | 0.388 | 0.1% | 3.00 | 4.4971 | 1010 |
| B4 | 448 | 22 | 53.0M | 1 | 108.5% | 0.212 | 42.4% | 1.53 | 4.5105 | 88 |
| B4 | 448 | 22 | 53.0M | 2 | 71.6% | 0.287 | 7.3% | 1.97 | 4.5105 | 176 |
| B4 | 448 | 22 | 53.0M | 4 | 28.6% | 0.347 | 0.2% | 2.53 | 4.5105 | 352 |
| B4 | 448 | 22 | 53.0M | 8 | 16.1% | 0.375 | 0.1% | 2.84 | 4.5105 | 704 |
| B4 | 448 | 22 | 53.0M | 16 | 12.0% | 0.382 | 0.1% | 2.99 | 4.5105 | 1408 |
| B5 | 384 | 30 | 53.1M | 1 | 112.8% | 0.209 | 40.9% | 1.52 | 4.5198 | 123 |
| B5 | 384 | 30 | 53.1M | 2 | 69.1% | 0.285 | 7.2% | 1.96 | 4.5198 | 247 |
| B5 | 384 | 30 | 53.1M | 4 | 27.4% | 0.345 | 0.1% | 2.52 | 4.5198 | 493 |
| B5 | 384 | 30 | 53.1M | 8 | 16.0% | 0.372 | 0.2% | 2.82 | 4.5198 | 987 |
| B5 | 384 | 30 | 53.1M | 16 | 11.5% | 0.375 | 0.1% | 2.98 | 4.5198 | 1974 |
| C1 | 1152 | 8 | 127.4M | 1 | 112.8% | 0.216 | 38.9% | 1.54 | 4.5039 | 32 |
| C1 | 1152 | 8 | 127.4M | 2 | 79.1% | 0.289 | 8.8% | 1.97 | 4.5039 | 64 |
| C1 | 1152 | 8 | 127.4M | 4 | 35.1% | 0.338 | 0.4% | 2.50 | 4.5039 | 128 |
| C1 | 1152 | 8 | 127.4M | 8 | 22.5% | 0.367 | 0.1% | 2.81 | 4.5039 | 257 |
| C1 | 1152 | 8 | 127.4M | 16 | 17.1% | 0.373 | 0.2% | 2.98 | 4.5039 | 514 |
| C2 | 960 | 12 | 132.7M | 1 | 115.4% | 0.216 | 38.5% | 1.53 | 4.5035 | 47 |
| C2 | 960 | 12 | 132.7M | 2 | 77.9% | 0.286 | 6.3% | 1.96 | 4.5035 | 95 |
| C2 | 960 | 12 | 132.7M | 4 | 36.7% | 0.341 | 0.7% | 2.49 | 4.5035 | 189 |
| C2 | 960 | 12 | 132.7M | 8 | 23.2% | 0.366 | 0.2% | 2.81 | 4.5035 | 379 |
| C2 | 960 | 12 | 132.7M | 16 | 18.9% | 0.373 | 0.2% | 2.97 | 4.5035 | 757 |
| C3 | 768 | 18 | 127.4M | 1 | 114.3% | 0.221 | 39.5% | 1.53 | 4.4879 | 72 |
| C3 | 768 | 18 | 127.4M | 2 | 76.3% | 0.296 | 8.3% | 1.96 | 4.4879 | 143 |
| C3 | 768 | 18 | 127.4M | 4 | 31.6% | 0.353 | 0.7% | 2.51 | 4.4879 | 287 |
| C3 | 768 | 18 | 127.4M | 8 | 18.4% | 0.381 | 0.1% | 2.83 | 4.4879 | 573 |
| C3 | 768 | 18 | 127.4M | 16 | 14.3% | 0.392 | 0.0% | 2.98 | 4.4879 | 1147 |
| C4 | 640 | 26 | 127.8M | 1 | 115.3% | 0.215 | 41.7% | 1.52 | 4.4889 | 105 |
| C4 | 640 | 26 | 127.8M | 2 | 73.1% | 0.290 | 7.2% | 1.97 | 4.4889 | 211 |
| C4 | 640 | 26 | 127.8M | 4 | 28.8% | 0.352 | 0.2% | 2.52 | 4.4889 | 421 |
| C4 | 640 | 26 | 127.8M | 8 | 17.4% | 0.381 | 0.0% | 2.84 | 4.4889 | 842 |
| C4 | 640 | 26 | 127.8M | 16 | 13.4% | 0.390 | 0.1% | 3.01 | 4.4889 | 1684 |
| C5 | 512 | 36 | 113.3M | 1 | 112.1% | 0.219 | 40.8% | 1.52 | 4.4867 | 142 |
| C5 | 512 | 36 | 113.3M | 2 | 67.6% | 0.293 | 6.5% | 1.97 | 4.4867 | 284 |
| C5 | 512 | 36 | 113.3M | 4 | 25.0% | 0.354 | 0.3% | 2.54 | 4.4867 | 568 |
| C5 | 512 | 36 | 113.3M | 8 | 13.9% | 0.379 | 0.1% | 2.86 | 4.4867 | 1136 |
| C5 | 512 | 36 | 113.3M | 16 | 9.9% | 0.388 | 0.0% | 3.02 | 4.4867 | 2272 |
§6Gate, cut and calendar history
{"passes": true, "today": "2026-08-06", "next_milestone": "M1_env_mup_done", "due": "2026-08-12", "hard_wall": "2026-08-29", "days_to_wall": 23}{"passes": true, "used_gpu_hours": 171.8436410319141, "occupancy_gpu_hours": 64.9795189098517, "mean_hours_per_run": 3.6117848808117854, "runs_remaining": -15, "projected_total": 194.3436410319141}{"argmin_w256": 0.004, "argmin_w640": 0.002, "passes": true, "when": "2026-08-05 23:47 UTC"}{"argmin_d4": 0.002, "argmin_d24": 0.002, "passes": true, "when": "2026-08-05 23:47 UTC"}{"passes": true, "checks": {"WER(C3,T=16) <= 0.30": {"pass": true, "value": 0.11250733636706733}, "WER(A3,T=16) <= 0.65": {"pass": true, "value": 0.1612674587067795}, "SIM-o(C3,T=16) >= 0.30": {"pass": true, "value": 0.4081370605202392}, "SIM-o(C3,T=16) >= cross baseline + 0.15": {"pass": true, "value": 0.4081370605202392}, "DegenRate(C3,T=16) <= 0.40": {"pass": true, "value": 0.0}}, "cross_speaker_baseline": 0.03381083719432354, "T_FLAT": false, "wer_C3_T1": 1.1411705989383842, "wer_C3_T16": 0.11250733636706733}{"passes": true, "configs_with_all_seeds": 15, "threshold": 12, "per_config_seeds": {"A1": [0, 1], "A2": [0, 1], "A3": [0, 1], "A4": [0, 1], "A5": [0, 1], "B1": [0, 1], "B2": [0, 1], "B3": [0, 1], "B4": [0, 1], "B5": [0, 1], "C1": [0, 1], "C2": [0, 1], "C3": [0, 1], "C4": [0, 1], "C5": [0, 1]}, "restarts": {}, "when": "2026-08-06 09:53 UTC"}{"passes": true, "n_runs": 45, "n_failing": 0, "differing_cell_fraction_range": [0.9819560669456067, 0.9888859832635983], "when": "2026-08-06 14:18 UTC"}{"passes": true, "n_budgets_passing": {"wer": 3, "sim": 3}, "when": "2026-08-06 14:21 UTC"}Cuts applied: none — no compute or calendar cut was triggered. Flags: none.
Protocol: protocol.html ·
theory: motivation.html · implementation:
implementation.html · decision:
DECISION.md · trail: LOG.md.