Wow! Neat way to express a noise! Just listened to first one and your observations. Highly likely that PS fluid is low and the color when checked on white paper shouldn't be dark. Usually clear to reddish.
No matter - this is likely a leak in the PS rack that can make it to the tire. Seeing just where will verify that. If just filled it may quiet down for now. It could be a hose to or from the rack or a seal on the rack. If slow enough (doesn't seem like it) you could try some tricks but I think you'll find it will need a new rack. If you don't allow this to run low on fluid and make noise too long you can save damage to the PS pump so get going and check and or fill as needed with proper fluid which is frequently same as ATF - automatic transmission fluid...........
T
Tom Greenleaf - MetroWest Boston - USA
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http://www.autoacsystems.com/tomgreenleaf/