From ZERO to HERO

日本藝人草(弓剪)剛日前酒醉在東京裸奔的事件，鬧的非常大，年輕人酒醉在公園鬧事，也讓東京警方傷透腦筋，現在他們計畫在公園內安裝一種新的噪音機，這個機器會發出高頻率的尖銳聲音，據說只有30歲以下的年輕人，才聽的到，東京打算在公園、公廁等地安裝，防止青少年半夜再來鬧事。
from : http://tw.news.yahoo.com/article/url/d/a/090512/8/1jdlr.html

鄉民提供了一個測試耳朵聽力的網站: http://www.ultrasonic-ringtones.com/
 

Can I hear these ultrasonic ringtones?
Find out just how far your ears can hear into the range of ultrasonic ringtones. Pretty much everyone should be able to hear the lowest tone (8kHz). Many people should be able to hear up to around 14.1kHz, from around 17kHz upwards we get into the range that only the under 20's can hear!
-	8kHz		Download to Phone/PC
-	10kHz		Download to Phone/PC
-	12kHz		Download to Phone/PC
A	14.1kHz		Download to Phone/PC
A#	14.9kHz		Download to Phone/PC
B	15.8kHz		Download to Phone/PC
C	16.7kHz		Download to Phone/PC
C#	17.7kHz		Download to Phone/PC
D	18.8kHz		Download to Phone/PC
D#	19.9kHz		Download to Phone/PC
E	21.1kHz		Download to Phone/PC
F	22.4kHz		Download to Phone/PC

Hearing test results
Choose the highest pitch tone that you could hear from the list below and click the 'Get result now' button

裡面提到一般人一定能聽到14.1kHz 而到17kHz以上
通常都是二十歲以下的青少年聽的到
一直懷疑我自己耳朵不好 但還是能聽到18.8kHz XD~