Stimulus types
VIPBench contains 9,800 voice pairs in 6 stimulus types, designed to span the perceptual identity landscape from "obviously same" to "obviously different" with controlled ambiguous regions in between.
The six types
| Type | Description | Metadata label | Pair count | P(same) shape |
|---|---|---|---|---|
| 1 | Same recording (reference compared with itself, segmented differently) | Same | 100 | concentrated near 1.0 |
| 2 | Same speaker, different recording | Same | 400 | high but spread |
| 3 | Same speaker, AI voice clone | Same | 400 | spreads across full range (clones with metadata-same label) |
| 4 | Different speakers, real recordings | Different | 400 | concentrated near 0.0 |
| 5 | Different speakers, AI voice clones | Different | 400 | concentrated near 0.0 |
| 6 | Continuously morphed voices | (no clean metadata label) | 8,100 | sweeps full range across the morph trajectory |
Total: 9,800 pairs, of which 1,700 carry a clean metadata same/different label (Types 1-5) and 8,100 are morph trajectories.
Note: Type 6's 8,100 pairs are 81 stimuli per reference speaker x 100 reference speakers. The 81 stimuli per reference speaker decompose as 4 within-group comparison speakers (matched on sociophonetic group, age group, and gender) x 2 distinct recordings per comparison x 10 morph scales between 0 and 1, plus 1 shared anchor at scale 1 (4 x 2 x 10 + 1 = 81). Per-stimulus trajectory metadata is in data/stimuli_interpol.csv.
Naming convention
Stimulus IDs in data/stimuli.csv and the audio filenames in data/audio/comparison/ follow the pattern:
- Types 1-5:
<type>_<reference_speaker>for type-1 same-recording pairs;<type>_<reference_speaker><variant>where the comparison clip varies across A-E for types 2-5.- Examples:
1_M01.wav(Type 1, M01),2_M01B.wav(Type 2, M01 with variant B),4_F03_F09B.wav(Type 4, reference F03 paired with F09 variant B).
- Examples:
- Type 6 morphs:
6_<source_speaker><variant>_<target_speaker><variant>_<scale>.wavwhere the variant letter (A-E) identifies the seed clip used for each speaker and<scale>is the interpolation level. Example:6_M05A_M03A_065.wavis a morph between M05's clip A and M03's clip A at scale 65.
The stimulus ID matches the comparison-audio basename (without .wav) and is the key into the embedding .npz files.
Voice cloning
Voice clones (Types 3 and 5) were generated with Cartesia (a state-of-the-art TTS system) seeded from a natural source clip of the speaker being cloned. The variant letter in the stimulus ID identifies the seed: a Type 3 clone shares its seed clip with the comparison clip of the matched Type 2 pair, and a Type 5 clone shares its seed with the matched Type 4 pair. For example, 3_F01B is seeded from the same F01B source clip that appears as the comparison in 2_F01B; 5_M01_F09B is seeded from the same F09B source clip that appears as the comparison in 4_M01_F09B. The reference clip itself was not used as the seed. The clone shares the metadata identity of the source speaker by construction; whether listeners hear the clone as that speaker is the per-pair question that the benchmark measures via P(same).
Voice morphing
Type 6 pairs were generated using the voice-morphing feature of the same Cartesia TTS system, interpolating the latent voice representation of the reference speaker toward each of 4 within-group comparison speakers (matched on sociophonetic group, age group, and gender). For each reference speaker x comparison speaker x recording (2 distinct recordings per comparison speaker), 10 morph scales between 0 and 1 were sampled, plus 1 shared anchor at scale 1. Per reference speaker: 4 x 2 x 10 + 1 = 81 stimuli, totaling 8,100 across 100 reference speakers. Stimulus IDs encode the two endpoints and the scale (e.g., 6_M05A_M03A_065 = morph between M05 and M03 with seed recordings A from each, at scale 65). Morphs have no clean metadata speaker label: at scale 0 the audio matches one speaker, at scale 100 the other, and intermediate scales sweep a perceptual continuum. This is the largest category in the dataset (8,100 of 9,800 pairs) and is designed to probe identity perception at fine resolution. Per-stimulus trajectory metadata (source speakers, recording variants, scale) is in data/stimuli_interpol.csv.
Why this design
The six types reflect three orthogonal axes:
- Metadata identity (same vs different speaker): Types 1-2-3 vs 4-5; Type 6 sweeps.
- Synthesis (real vs AI-generated): Types 1-2-4 vs 3-5; Type 6 is morphed.
- Ambiguity (concentrated vs spread
P(same)): Types 1, 4, 5 are concentrated; Types 3 and 6 sweep, exposing where listener perception diverges from the metadata label.
Types 3 and 6 are where perceptual and metadata identity most often disagree, making them the centerpiece of the benchmark's perception-vs-metadata contrast.