When using the internal mic, place the iPhone as close as possible to the clock movement or where it is the loudest. This will vary with each type of clock. The closer the positioning the more accurate the hearing of the ticking sound. You can select any of the iPhone's built-in microphones: Front, Rear or Bottom. A particular mic will work better depending on placement, clock type and design.
The external EarPods' microphone performs much better: You can place the mic inside the clock case, closer to the movement, while having more freedom to operate the app. This also provides better isolation of the clock ticking from ambient noise.
The internal and headset microphones function best in a quiet environment. Ambient noise may affect the accuracy of the measurement and cause incorrect results. For best results, we recommend the use of an external piezo-acoustic contact microphone. Learn More