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RESEARCH PAPER / 2026-02-12

Moonshine v2: Ergodic Streaming Encoder ASR for Latency-Critical Speech Applications

Manjunath Kudlur, Evan King, James Wang ...Full author list in the original paper.

Moonshine AI · arXiv

Affiliations: Moonshine AI

Abstract

Latency-critical speech applications (e.g., live transcription, voice commands, and real-time translation) demand low time-to-first-token (TTFT) and high transcription accuracy, particularly on resource-constrained edge devices. Full-attention Transformer encoders remain a strong accuracy baseline for automatic speech recognition (ASR) because every frame can directly attend to every other frame, which resolves otherwise locally ambiguous acoustics using distant lexical context. However, this global dependency incurs quadratic complexity in sequence length, inducing an inherent "encode-the-whole-utterance" latency profile. For streaming use cases, this causes TTFT to grow linearly with utterance length as the encoder must process the entire prefix before any decoder token can be emitted. To better meet the needs of on-device, streaming ASR use cases we introduce Moonshine v2, an ergodic streaming-encoder ASR model that employs sliding-window self-attention to achieve bounded, low-latency inference while preserving strong local context. Our models achieve state of the art word error rates across standard benchmarks, attaining accuracy on-par with models 6x their size while running significantly faster. These results demonstrate that carefully designed local attention is competitive with the accuracy of full attention at a fraction of the size and latency cost, opening new possibilities for interactive speech interfaces on edge devices.

The following analysis is generated by AI and may contain errors. It is separate from the authors’ abstract and is not peer review.

Research summary

The main contribution of this paper is the introduction of Moonshine v2, an innovative ergodic streaming encoder that effectively balances low latency and high accuracy in ASR tasks. This work represents a substantial advancement in the field, particularly for applications requiring real-time processing on resource-constrained devices.

Methodology

The paper introduces Moonshine v2, an ergodic streaming encoder for automatic speech recognition (ASR) that utilizes sliding-window self-attention to mitigate the latency issues associated with full-attention Transformer models. This approach is particularly relevant for edge devices where computational resources are limited. The methodology is well-articulated, focusing on the balance between maintaining local context and reducing latency, which is a critical factor in real-time applications. The authors provide a solid theoretical foundation for their approach, detailing how their model achieves low time-to-first-token (TTFT) while preserving accuracy.

Results & evaluation

The experiments conducted demonstrate that Moonshine v2 achieves state-of-the-art word error rates across standard benchmarks. The authors compare their model's performance against larger models, highlighting its efficiency in both speed and accuracy. The results are compelling, showing that the proposed method can compete with significantly larger models, which is a notable achievement in the field of ASR. However, details on the datasets used and the specific experimental setups could be elaborated further for clarity.

Reproducibility

The paper lacks detailed implementation specifics that would aid in reproducibility. While the results are promising, the absence of code or a clear description of the experimental setup limits the ability for other researchers to replicate the findings. Providing a GitHub repository or supplementary materials would enhance the paper's reproducibility.

Limitations

One limitation of the proposed model is its reliance on local attention mechanisms, which may not capture long-range dependencies as effectively as full attention models. Additionally, the paper does not address potential scenarios where the model might underperform, such as in highly complex acoustic environments. The scalability of the model in terms of adapting to various languages or dialects is also not discussed.

Broader impact

The implications of this research are significant, particularly for applications in live transcription, voice commands, and real-time translation on edge devices. By reducing latency while maintaining accuracy, the model opens up new possibilities for interactive speech interfaces, which could enhance user experiences in various domains, including accessibility technologies and smart devices. The main contribution of this paper is the introduction of Moonshine v2, an innovative ergodic streaming encoder that effectively balances low latency and high accuracy in ASR tasks. This work represents a substantial advancement in the field, particularly for applications requiring real-time processing on resource-constrained devices.

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