A child caught in a giant oil tank crying for help. More specifally, two sginals convolved with the impulse response of a large WW2 era oil tank provided by acs272. It's the longest echo from any location in the world. I used the 6th response, found here: <a href="http://freesound.org/people/acs272/sounds/214220/" rel="nofollow">http://freesound.org/people/acs272/sounds/214220/</a> The two voice signals belong to brandonreese ('Help Me') and girlhurl ('Hello') respectively. <a href="http://freesound.org/people/brandonreese/sounds/331367/" rel="nofollow">http://freesound.org/people/brandonreese/sounds/331367/</a> <a href="http://freesound.org/people/girlhurl/sounds/339157/" rel="nofollow">http://freesound.org/people/girlhurl/sounds/339157/</a><br/>hello_reverb.ogg<br/>聲道：1<br/>類型：ogg<br/>response、impulse、hello、reverb、enormous<br/>響應、衝動、你好、混響、巨大<br/>資料來源：freesound ( https://freesound.org )