Firstsong: Baby Heartbeat

By Jan Daniel Naftanaila on AppTrack Ninja.

Real fetal sound, or silence

You should be skeptical. Everybody who reviews an app like this one is. Half of the reviews in this whole category say the same sentence: I could not hear anything, and the app showed a number anyway. That is the problem Firstsong was built to fix, and the fix is not a better microphone. It is a rule. HOW IT WORKS Put your headphones in, lie down, and hold the phone flat against bare skin, low and central, below the navel. Firstsong measures the room first and refuses to start if it is too loud. Then it listens: it throws away everything outside 20 to 200 Hz, looks for the interval that repea…

Categories: Health & Fitness

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