Speech-to-text translation has many potential applications for low-resource
languages, but the typical approach of cascading speech recognition with
machine translation is often impossible, since the transcripts needed to train
a speech recognizer are usually not available for low-resource languages.
Recent work has found that neural encoder-decoder models can learn to directly
translate foreign speech in high-resource scenarios, without the need for
intermediate transcription. We investigate whether this approach also works in
settings where both data and computation are limited. To make the approach
efficient, we make several architectural changes, including a change from
character-level to word-level decoding. We find that this choice yields crucial
speed improvements that allow us to train with fewer computational resources,
yet still performs well on frequent words. We explore models trained on between
20 and 160 hours of data, and find that although models trained on less data
have considerably lower BLEU scores, they can still predict words with
relatively high precision and recall---around 50% for a model trained on 50
hours of data, versus around 60% for the full 160 hour model. Thus, they may
still be useful for some low-resource scenarios.

通过实验研究，我们发现在资源有限的情况下，从字符级识别转化成单词级可以显著提高低资源语言语音翻译的速度，并且在训练数据相对较少的情况下，仍然可以实现相对较高的词汇精度和召回率。