2013-12-27

AM development

Sparse DNN

• Optimal Brain Damage(OBD).

1. Online OBD held.
2. OBD + L1 norm start to investigation.

• Efficient computing

1. Conducting rearrangement the matrix structure and compose zero blocks by some smart approaches, leading to better computing speed.

Efficient DNN training

1. Moment-based training. With m=0.2 performs the best on WER. 6.8% improvement on WER. Other settings are tried on 0.05,0.1,0.2,..0.6,0.8,1.0.
2. Asymmetric window: left 20, right 5. NN accuracy increase by 7%, however WER is a bit worse than the baseline. Move back to Tencent 100h training.
3. Frame-skipping is on implementation.

Optimal phoneset

1. Experiment 3 phone sets: Tencent, CSLT, PQ
2. Some errors occur in pure CHS experiments

Engine optimization

• Investigating LOUDS FST. On progress.

LM development

NN LM

• Trained with 500M QA data, 110k vocabulary.
• Tested on number of hidden layers (DNN), performance is better for some tests, but not for others.
• Tested on larger projection layer, from 256 to 384, the performance is consistently improved.

Embedded development

• Embedded stream mode on progress.

Speech QA

• SP-QA accuracy 45.14% in all the input (18*199).
• Investigate the error patterns:

• 70% errors are caused by incorrect name entity recognition. Working on entity recovery (character, pinyin, ... distance penalty).
• 8% errors are caused by English names. Use class-based LM to solve the problem. Ready to work.
• Use N-best to recover errors in QA.