It is very difficult to guess the problem with the inputs you have provided. There are many factors that may contribute to the issue.
1. How are you connecting the microphone to PSoC? As microphone produces an AC signal, you cannot directly connect the signal to the PSoC input w.r.t VSS. It has to be biased to AGND and then connected to PSoC. Check out the below blog article that shows some methods of connecting an AC signal to the PSoC input.
2. Similarly, once you bias your input to AGND, the output on the anlog buffer will also have a DC component equal to AGND. So, you have to connect the output to the speaker through a capacitor.
3. Check the gain of the PGA is sufficient to produce a sound on the speaker
The PSoC Hacker