Current audio pre-training seeks to learn unified representations for broad audio understanding tasks, but it remains fragmented and is fundamentally bottlenecked by its reliance on weak, noisy, and scale-limited labels. Drawing lessons from vision's foundational pre-training blueprint, we argue that the audio field must first establish its own large-scale, strong supervision framework. We introduce a new data-centric pipeline that leverages a high-fidelity captioner to create SOTA-quality captions and the first Unified Tag System (UTS) that bridges speech, music, and environmental sounds. We then conduct a systematic comparative study of different pre-training objectives on these strong source data. Our experiments suggest that data quality and coverage are the primary drivers of performance, while the choice of objective dictates downstream task specialization.
Figures & tables
Figure 1: An overview of our method. (a) Audio Tagging Pipeline: we generate tags by processing raw audio through Qwen3-Omni-Captioner [ 87 ] and an LLM Parser [ 90 ] . (b) Pre-Training Pipeline: the audio encoder is then pre-trained using these tags with two supervision objectives: a discriminative multi-tag classification (MTC) Objective (using a linear classifier) and a generative parellel decoding (PAR) Objective (using a text decoder with a bidirectional mask).
Figure 2: Analysis of our tag system. (a) Word cloud of the most frequent tags in our parsed tags, illustrating its diverse vocabulary. (b) t-SNE comparison of our UTS-1.5k (blue) and AudioSet (red), demonstrating our system’s superior semantic coverage and density. (c) The characteristic long-tail tag frequency distribution of all parsed tags.
Dataset
Audio Coverage
Tag Size
Data Size
AudioSet [ 29 ]
General events (incl. speech, music)
527
∼ 2M
FSD-50k [ 27 ]
General sound events
200
∼ 50k
VggSound [ 9 ]
General sound events
309
∼ 200k
CREMA-D [ 8 ]
Speech
6
∼ 7k
MagnaTagATune [ 82 ]
Music
50
∼ 24k
Ours
Unified (Speech, Music, Env. Sounds)
800/1k/1.5k/2k/3k
∼ 400k
Table 1: Comparison of existing audio tagging datasets.
Methods
Label
Linear Probing
Audio-language Alignment
Captioning
Retrieval
FSD-50k
VggSound
AS-Strong
VoxCeleb2
CREMA-D
MTAT
NSynth
AC
PSC
MC
AC
PSC
MC
SSL Models
BEATs [ 12 ]
-
0.565 †
-
0.034 †
-
-
0.400 †
75.90 †
-
-
-
-
-
-
Wav2vec 2.0 [ 3 ]
-
0.342 †
-
-
51.60
56.10
0.317 †
40.20 †
-
-
-
-
-
-
MERT [ 51 ]
-
-
-
-
-
-
0.402 †
72.60 †
-
-
-
-
-
-
Table 2: Main results on linear probing (with mean-pooling) and audio-language alignment. The linear probing tasks span general audio (FSD-50k [ 27 ] , VggSound [ 9 ] , AudioSet-Strong [ 37 ] ), speech (VoxCeleb2 [ 15 ] , CREMA-D [ 8 ] ), and music (MagnaTagATune [ 82 ] , NSynth [ 25 ] ). See Supplementary Material Sec. 8 for full details of evaluation datasets and metrics. For audio-language alignment, AC, PSC, and MC refer to the AudioCaps [ 44 ] , ParaSpeechCaps [ 21 ] , and MusicCaps [ 1 ] , respectively. We bold the best score among our proposed models. Baseline scores that are underlined are surpassed by their corresponding “Ours” counterpart. † denotes scores quoted from prior work with a consistent evaluation setup.
Methods
Open-formed QA
Sound
Speech (emotion/gender/age)
Music
Baselines
MTC (AudioSet)
7.01
47.16/ 25.90 / 47.27 / 45.06 / 37.24
5.61
Contrastive-scratch [ 78 ]
5.69
29.61 /48.79/ 55.25 /84.85/86.59
5.99
Captioning-scratch [ 78 ]
6.25
22.93 /37.40/70.20/78.93/40.14
5.73
Our Tag-Oriented Pre-Trained Models
Table 3: Open-formed Question Answering (QA) Results on the AIR-Bench [ 91 ] . The Sound and Music columns report 10-point scores from open-ended questions, evaluated by GPT-4o [ 62 ] . The five scores in the Speech column correspond to the classification accuracy on the Emotion-MELD, Emotion-IEMOCAP, Gender-MELD, Gender-common, and Age tasks, respectively.
Table 5: Overview of the public datasets constituting CaptionStew. The table summarizes their scale, domain coverage, audio sources, and diverse captioning pipelines (from human annotation to LLM generation).
Figure 8
Evaluation Dataset
Task
#samples
#class
train
eval
Metrics
FSD-50k
Multi-label audio event classification
37,168 / 10,231
200
✓
✓
mAP
VggSound
Single-label audio event classification
183,730 / 15,446
309
✓
✓
accuracy
VoxCeleb2
Speaker identification
1,092,009 / 36,693
5,994
✓
✓
accuracy
CREMA-D
Speech emotion recognition
6,030 / 706
6
✓
✓
accuracy
MagnaTagATune
Music tagging
19,425 / 4,856
50
✓
✓
mAP
NSynth
Musical instrument classification
289,205 / 4,096
11
✓
✓
accuracy
Table 6: Overview of the evaluation datasets used for assessing audio representation quality. † Evaluated by GPT-4o following the AIR-Bench protocol. ‡ Synthesized from publicly available speech datasets [ 2 , 7 , 8 , 54 , 63 ] using fixed question templates.
Methods
Label
Linear Probing
Audio-language Alignment
Captioning
Retrieval
FSD-50k
VggSound
AS-Strong
VoxCeleb2
CREMA-D
MTAT
NSynth
AC
PSC
MC
AC
PSC
MC
SSL Models
BEATs [ 12 ]
-
0.565 †
-
0.034 †
-
-
0.400 †
75.90 †
-
-
-
-
-
-
Wav2vec 2.0 [ 3 ]
-
0.342 †
-
-
51.60
56.10
0.317 †
40.20 †
-
-
-
-
-
-
MERT [ 51 ]
-
-
-
-
-
-
0.402 †
72.60 †
-
-
-
-
-
-
Table 7: Complete results on linear probing (with mean-pooling) and audio-language alignment. The linear probing tasks span general audio (FSD-50k [ 27 ] , VggSound [ 9 ] , AudioSet-Strong [ 37 ] ), speech (VoxCeleb2 [ 15 ] , CREMA-D [ 8 ] ), and music (MagnaTagATune [ 82 ] , NSynth [ 25 ] ). For audio-language alignment, AC, PSC, and MC refer to the AudioCaps [ 44 ] , ParaSpeechCaps [ 21 ] , and MusicCaps [ 1 ] , respectively. We bold the best score in our tag-oriented models and audio-language models respectively. Baseline scores that are underlined are surpassed by their corresponding “Ours” counterpart. † denotes scores quoted from prior work with a consistent evaluation setup.
Methods
Linear Probing
Open-formed QA
FSD-50k
VggSound
VoxCeleb2
CREMA-D
MTAT
NSynth
Sound
Speech (emotion/gender/age)
Music
Baselines
MTC (AudioSet)
0.656
56.23
58.76
72.52
0.405
74.80
7.01
47.16/ 25.90 / 47.27 / 45.06 / 37.24
5.61
Contrastive-scratch [ 78 ]
0.534
46.79
70.18
69.97
0.385
70.19
5.69
29.61 /48.79/ 55.25 /84.85/86.59
5.99
Captioning-scratch [ 78 ]
0.483
43.43
44.51
66.29
0.382
68.31
6.25
22.93 /37.40/70.20/78.93/40.14
5.73
Our Tag-Oriented Pre-Trained Models
Table 8: Complete results on linear probing (with multi-head attention pooling) and open-formed QA. The Sound and Music columns report 10-point scores on open-ended questions from AIR-Bench, evaluated by GPT-4o [ 62 ] . The five scores in the Speech column correspond to the classification accuracy on the Emotion-MELD, Emotion-IEMOCAP, Gender-MELD, Gender-common, and Age tasks, respectively.