Attuned Resonance Voice Tone

Attuned Resonance — Voice Tone Classifier

The 4th model in the Attuned Resonance call-center cascade. Detects caller emotion across 10 classes from short audio clips (2–8 seconds).

Status: v1 (frozen-backbone baseline). Full fine-tune planned for v2.2. Hopeful and urgent classes are undersampled — backfill pending. Part of: Attuned Resonance — a 4-model cascade for inbound call routing.

Model Description

Architecture	facebook/wav2vec2-base (frozen, 95M params) → mean-pool over hidden frames (masked) → 768→256 GELU+dropout(0.3)→10 MLP head
Training data	6,021 synthetic clips generated by ElevenLabs eleven_v3 with audio-tag labels ([angry], [hopeful], etc.)
Sample rate	16 kHz mono (resampled from 44.1 kHz mp3)
Output	softmax over EMOTION_LABELS (10 classes), with predict() returning the top label, confidence, and full probability distribution

Emotion taxonomy

EMOTION_LABELS = [
    "angry", "frustrated", "sad", "calm", "anxious",
    "satisfied", "confused", "neutral", "urgent", "hopeful",
]

Each label is mapped to one or more ElevenLabs v3 audio tags during synthesis. The synthesis instruction is the ground-truth label — no manual annotation. See models/voice_tone/labels.py for the tag map.

Intended use

• Cascade integration: feed the 10-class probability vector to the Outcome Predictor (planned v2.2 fusion).
• Standalone emotion detection on short call-center audio.
• Research and benchmarking on synthesis-as-label vs human-labeled emotion datasets.

Out-of-scope

• Production routing decisions without human-in-the-loop review.
• Languages other than English.
• Long-form audio (clips > ~30 seconds — the mean-pool collapses too much).
• Real spontaneous speech until v2.2 fine-tune validates real-world transfer.

Training details

Hyperparameter	Value
Backbone	facebook/wav2vec2-base (frozen — requires_grad=False for all backbone params)
Head	768 → 256 (GELU + dropout 0.3) → 10
Optimizer	AdamW, lr=1e-3, weight_decay=1e-4
Loss	Cross-entropy
Sampler	WeightedRandomSampler (compensates for hopeful 4.3× imbalance)
Epochs	20
Batch size	64
Split	Voice-stratified: 26 train / 4 val / 4 test voices (deterministic seed=42)
Hardware	CPU (Intel, 12 cores). Frozen backbone caches features once → linear-head training is seconds.

Evaluation

Held-out test split: 4 voices the model never saw during training. The voice-stratified split is the right benchmark for an emotion classifier — it forces the model to generalize across speakers rather than lean on per-voice timbre cues.

Metric	Value
Best val accuracy	64.7%
Test accuracy	59.9%
Random baseline (10-class)	10.0%

Per-class test accuracy

Class	Acc	n	Notes
frustrated	91.2%	80	Distinctive prosody — easy
angry	85.0%	80	High arousal — easy
urgent	77.8%	72	Distinctive — easy
hopeful	73.7%	19	Small test n — high variance
neutral	67.5%	80	Tag-free baseline
satisfied	56.2%	80
sad	50.0%	80
calm	38.8%	80	Confused with anxious / neutral
anxious	36.2%	80	Confused with confused / sad
confused	35.0%	80	Confused with anxious / calm

The high/low split is interpretable: extreme arousal states (angry, frustrated, urgent) have distinctive prosody and are easy. Mid-arousal states (calm, anxious, confused) share acoustic features in the frozen wav2vec2 representation. A full fine-tune (v2.2) is the obvious lever.

Limitations

1. Synthesis-as-label prior. The classifier learns "what eleven_v3 thinks [angry] sounds like." Real callers do not speak with explicit synthesis tags; their prosody distribution may differ. Real-audio held-out evaluation is the v2.2 milestone.
2. Class imbalance. Hopeful: 154 clips (vs 660 for most classes). Test set has only 19 hopeful examples — metrics for that class are noisy.
3. 34 voices, English only. No accent / age / gender audit. ElevenLabs voices skew accent-neutral.
4. Short clips only. Mean-pooled embedding collapses long temporal structure. For long-form calls, a sliding-window approach is needed.
5. Frozen backbone ceiling. The backbone wasn't trained on emotion-discriminative objectives; mid-arousal class confusion reflects that.

Usage

from models.voice_tone.inference import VoiceToneClassifier

clf = VoiceToneClassifier.load('trained_models/voice_tone')
result = clf.predict('path/to/clip.mp3')

# result.emotion       -> 'angry'
# result.confidence    -> 0.953
# result.probs         -> {'angry': 0.953, 'urgent': 0.022, ...}

Files

• head.safetensors — trained head weights (256-hidden MLP).
• config.json — architecture config + emotion labels.
• metrics.json — full training history + per-class test metrics.

The wav2vec2 backbone is loaded from facebook/wav2vec2-base at inference time; we do not redistribute it.

Citation

@misc{rubin2026attunedresonance,
  title  = {Attuned Resonance: A Multi-Model Cascade for Inbound Call-Center Routing},
  author = {Theodore Rubin},
  year   = {2026},
  url    = {https://github.com/tedrubin80/CEPM}
}

License

CC-BY-NC-4.0 (research/educational use). Not a production system.