Sign language serves as the primary communication medium for over 466 million people with disabling hearing loss worldwide, projected to exceed 900 million by 2050 [1]. As a complete linguistic system with unique grammar and cultural nuances, it poses significant challenges for automated translation [2]. Deep learning has advanced SLT from isolated gesture recognition using convolutional neural networks (CNNs) [3] to sequence modeling with recurrent networks and transformers [4], [5]. Ensemble approaches leverage architectural diversity for improved performance [6], yet challenges persist in balancing accuracy, real-time efficiency, continuous signing handling, dataset diversity, and multilingual generalization [2], [7]. This study addresses these gaps through a hybrid ensemble framework. Objectives include developing an efficient architecture, enhancing continuous interpretation, improving robustness via augmentation, validating performance, and assessing deployability. Contributions comprise a novel adaptive fusion ensemble, superior continuous recognition (F1=0.82), benchmark-setting metrics (98.6% accuracy, 65 ms latency), and deployment guidelines. The work holds broad impact for education, healthcare, employment, and social inclusion [8], while preserving linguistic diversity and informing multimodal AI advancements [9].
Related Work
SLT research has progressed from hand-crafted features and hidden Markov models to deep learning paradigms [2]. CNNs like Efficient Net [10] and ResNet [11] dominate spatial feature extraction [3], [6]. Temporal modeling employs LSTMs [12], TCNs, or transformers [4], [5]. Hybrid CNN-transformer models integrate strengths [13], while ensembles enhance robustness [9], [6]. Multimodal inputs, including MediaPipe key points [14] and sensor fusion [15], improve invariance. Data augmentation mitigates scarcity [9], with metrics encompassing accuracy, BLEU [16], WER, F1, and latency [2]. Persistent gaps include real-time constraints, continuous signing, limited diversity, cross-linguistic transfer, and deployment robustness [7], [2]. This work bridges them via a diverse ensemble with key point preprocessing and comprehensive augmentation.
METHODOLOGY
System Architecture
The ensemble integrates:
EfficientNetB0: Lightweight spatial extractor with MBConv blocks; ImageNet-pretrained [10]. ResNet50: Deep residual network for hierarchical features; ImageNet-pretrained [11]. Transformer: 6-layer encoder-decoder (8 heads, 512-dim) with positional encoding and cross-attention for sequences [4]. Attention Fusion Layer: Dynamically weights features based on confidence and context [9]. Inputs are key point sequences and frames; outputs are gloss predictions or text translations.
Datasets
Combined WLASL [17] and MSASL [6]: 8,500 videos, 2,500 glosses, 150+ signers, 45 hours. Stratified split: 60% train, 20% validation, 20% test. Preprocessing and Augmentation Key points: Media Pipe Holistic extracts 42 hand, 468 face, 33 pose landmarks [14]. Normalization: 224×224 RGB frames. Segmentation: Motion thresholding for continuous sequences. Augmentation: Spatial (rotation ±15°, scaling 0.85-1.15×), temporal (speed 0.8-1.2×), occlusion, noise, blur. 3.4 Training and Implementation NVIDIA RTX 3090; TensorFlow 2.10. Adam optimizer (lr=10^{-4}-10^{-3}); batch size 32; 70 epochs with early stopping. Staged training: isolated components, joint fine-tuning, ensemble fusion. Combined loss: cross-entropy (classification/sequence) + attention regularization.
RESULTS
Training converged at epoch 67 (68 hours). Validation/test accuracy: 98.6%. Comparison with State-of-the-Art Table 1 compares key methods.
Table 1. Performance comparison.
|
Method |
Year |
Accuracy (%) |
BLEU |
WER (%) |
F1 (Continuous) |
Latency (ms/frame) |
|
Chung [7] |
2022 |
91.7 |
0.53 |
12.0 |
0.62 |
90 |
|
Shi et al. [13] |
2022 |
93.8 |
0.68 |
- |
0.73 |
105 |
|
Albert et al. [6] |
2023 |
99.8 |
0.68 |
6.5 |
N/A |
120 |
|
Alkhoraif [5] |
2025 |
95.2 |
0.61 |
8.7 |
0.70 |
160 |
|
Proposed |
2025 |
98.6 |
0.75 |
5.4 |
0.82 |
65 |
Superior in BLEU (+10.3% over [6]), F1, and latency (-46% vs. [6]).
4.2 Ablation Study Table 2 shows component impacts.
Table 2. Ablation results.
|
Configuration |
Accuracy (%) |
BLEU |
F1 |
Latency (ms/frame) |
|
EfficientNetB0 only |
94.2 |
0.62 |
0.68 |
35 |
|
ResNet50 only |
95.8 |
0.65 |
0.71 |
58 |
|
Transformer only |
91.5 |
0.70 |
0.75 |
95 |
|
EfficientNetB0 + ResNet50 |
97.1 |
0.69 |
0.74 |
48 |
|
EfficientNetB0 + Transformer |
96.3 |
0.72 |
0.78 |
55 |
|
ResNet50 + Transformer |
97.5 |
0.73 |
0.79 |
82 |
|
Full ensemble |
98.6 |
0.75 |
0.82 |
65 |
Ensemble yields synergistic gains. Continuous and Multilingual Performance Continuous F1: 0.82 overall; degrades gracefully with sequence length (0.91 short, 0.71 very long). Multilingual: 99.1% (ASL trained), 92.5% (BSL), 78.4% zero-shot (ISL).
Robustness and Efficiency Environmental drops mitigated by augmentation (max -15.4% combined challenges). Inference: 65 ms/frame (GPU, 15.4 fps); model size 475 MB. Statistical significance: p<0.001 vs. baselines (5 runs).
Error analysis: Confusions in similar signs; attention focuses on key frames.
DISCUSSION
The ensemble balances accuracy and efficiency via EfficientNetB0's lightness, ResNet50's depth, and transformer's sequencing [4], [10], [11]. Translation gains stem from cross-attention aligning signs to text. Continuous recognition addresses co-articulation via temporal segmentation.
LIMITATIONS
Dataset biases (ASL-dominant); cultural/pragmatic gaps; extreme-condition degradation. Implications: Real-time apps in education/healthcare; complements human interpreters. Ethical: Privacy (key points reduce risks), fairness monitoring, community involvement.
Future: Multimodal fusion [15], few-shot adaptation, bidirectional translation, field trials.
CONCLUSION
The proposed ensemble advances SLT with 98.6% accuracy, 0.75 BLEU, 0.82 continuous F1, and 65 ms latency—setting new benchmarks for practical, inclusive systems. It promotes accessibility while highlighting needs for diverse data and ethical deployment.
REFERENCE
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Musbahu Yunusa Makama**
10.5281/zenodo.17627834