There are posts saying deepspeech modal only supports 8k sample format, so I accommodated all the voice sample rate to 8k. However, the performance was much worse that the previous one. Here is the code of accommodating the sample rate:
for file in *.wav;do
#echo $file
c=${file}
#echo $c
sox $c -r 8000 new_$c
rm -rf $c
mv new_$c $c
done