Firstly, there are such applications. On habré were discussed. People use even.
Or rather trying to use it, because:
Secondly, they work sucks.
Using the conventional microphone
of a smartphone, which in fact is confined to the transmission of speech only and speech - there is even the music sucks is written through him a lot and full of sound information does not get.
And by the way your reference or a lie, or you not so understood
It is defined through the reflection generated by the mobile ultrasonic signal.
In conventional mobile no components capable of generating ultrasound.
At least stable enough and strong enough and sufficiently focused to plus it was nezavisla the model of smartphone - definitely not.
Perhaps the researchers hooked to the additional mobile device. Well, or used completely independent from a smartphone, but still external to the mobile emitter of ultrasound.