The microphone in Apple's devices is very good and you may find that excess environmental noise has an effect on the accuracy of the text returned.
Hold the microphone button to pause detection, this will help you to avoid catching your own conversations, resume detection by lifting your finger.
For our Ghost Hunter friends this tool will allow you to use your Apple device to listen for EVPs.
The estimated accuracy of the data is listed with the translation along with the EMF reading at the time of the capture.
Don't forget to scroll, your entire session may continue beyond the screen, so scroll down to see the latest results.