If i want to change the SAMPLE_RATE from 16000 to 8000, how can i do?

[tongma]

If i want to change the SAMPLE_RATE from 16000 to 8000, how can i do?
I tried to change SAMPLE_RATE from 16000 to 8000, and change the code
private static final int SAMPLE_RATE = 16000;
private static final int BITS_PER_SAMPLE = 16;

   private static final int SAMPLE_RATE = 16000;

        soundtouch.setSampleRate(16000);
        soundtouch.setChannels(1);

to
private static final int SAMPLE_RATE = 8000;
private static final int BITS_PER_SAMPLE = 16;

   private static final int SAMPLE_RATE = 8000;

        soundtouch.setSampleRate(8000);
        soundtouch.setChannels(1);

then the voice is not right.

Which code should i change ?
would you please kindly help to give me a reply soon? Thanks in advance!