I've purchased and experimented with a few of the available apps with disappointing results. I've even tried mounting a quality microphone in a suction cup to try and isolate the sound. The results are always inconsistent. I have not tried any of the home testing devices Lepsi etc. A big factor is ambient noise. I'm not an audio engineer but I think the signal processing in the apps is an issue, it can't compare to a dedicated device. Best, Martin

Microphone in suction cup