iFrames appearing skewed

I am building a site with Helena that has a lot of iFrames in it from different sources. Despite the dimensions in the iFrame snippet being correct, they all appear with the wrong ration - appearing long and thin instead of rectangular. I have tried on posts and pages with iFrames from youtube, soundcloud and other places and it is the same with all of them. Can anyone advise how to get them to appear in the right size as it is key to my site? examples can be seen here: http://itsthelisteningthatcounts.axnscollective.org/city-sounds/