What's this sound?

[TestudoToTetsudo]

At 1:00-1:05 in the video (I'm sorry for the brakes noise in the background, its the best I could find in a quick search on YouTube), there's a two-tone chime noise in the station.  I heard this a lot when I was in Tokyo last year too, but couldn't pinpoint what the sound was for.  Does anyone know?  Thanks!

 

[bikkuri bahn]

I'm not 100% sure, due to the background noise, but it's probably a chime for the blind warning about steps going down (also very common at subway station entrances), or an elevator door opening.

[TestudoToTetsudo]

Thanks, it was the two-tone chime, one with a higher pitched tone, then a pause for a second or two, then a lower pitched tone.

 

That could make sense...I remember I heard this a lot at the faregate level in Otsuka Station and there were escalators nearby.  And there are stairs on the platform too...