Ultrasonic ringtone into your cellphone

Today's blog from below URL.

http://lifehacker.com/5312062/use-an-ultrasonic-ringtone-for-stealthy-notifications

This blog said that you can download ultrasonic ringtone into your cellphone for your stealthy notification.
It's interesting !!
Sometimes, I feel annoyed by someone's sudden ringtone in the public place such as in the train so I hope this notification improve people's manner.

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[Corrected one]

Today's blog from below URL.

http://lifehacker.com/5312062/use-an-ultrasonic-ringtone-for-stealthy-notifications

This blog said that you can download ultrasonic ringtone into your cellphone for stealthy notification.
It's interesting !!
Sometimes, I feel annoyed by someone's sudden ringtone in the public place such as inside the train so I hope this notification would improve people's manner.