[Note] Understand the role of self attention for efficient speech recognition
* Self-attention plays two role in the success of Transformer-based ASR * The "attention map" in self-attention module can be categorize to 2 group * "phonetic"(vertical) and "linguistic"(diagonal) * Phonetic: lower layer, extract phonologically meaningful global context * Linguistic: higher layer, attent to local context * -> the phonetic variance is standardized in lower…