  Numerous studies have investigated the effectiveness of neural network
quantization on pattern classification tasks. The present study, for the first
time, investigated the performance of speech enhancement (a regression task in
speech processing) using a novel exponent-only floating-point quantized neural
network (EOFP-QNN). The proposed EOFP-QNN consists of two stages:
mantissa-quantization and exponent-quantization. In the mantissa-quantization
stage, EOFP-QNN learns how to quantize the mantissa bits of the model
parameters while preserving the regression accuracy using the least mantissa
precision. In the exponent-quantization stage, the exponent part of the
parameters is further quantized without causing any additional performance
degradation. We evaluated the proposed EOFP quantization technique on two types
of neural networks, namely, bidirectional long short-term memory (BLSTM) and
fully convolutional neural network (FCN), on a speech enhancement task.
Experimental results showed that the model sizes can be significantly reduced
(the model sizes of the quantized BLSTM and FCN models were only 18.75% and
21.89%, respectively, compared to those of the original models) while
maintaining satisfactory speech-enhancement performance.
