We have just recently released a cool new app Sentector

★★★ Introducing Sentector ★★★

☆★☆ Train your Android to alert you when it hears a SPECIFIC sound at your home, office or lab. Unlike other apps, random loud noises such as a dog barking or your own voice, will not set-off the alert.
Use in a noisy lab setting as a 24-hour security system to alert you when a sensitive machine sets off an alarm. Or use at home and train it to listen when the water alarm goes off if there is flooding in your basement ☆★☆

Best Features:

◉ A sound detector that is trained to listen to a specific sound
◉ Image surveillance: it will email a picture of the alarm is triggered
◉ A surveillance log which allows you to review when the alarm was set off
◉ An email warning alert if your power goes out

Link to Google Play Store: https://play.google.com/store/apps/details?id=com.mobisys.android.sentector&hl=en
Requirements: Android 3.0 and Up.
Available for Android.
I recommend you to download this free and awesome app.