simplexml_load_file and soap wrappers

[how]

I've received a file with some soap wrappers.[<soap:Envelope
xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Header>]
The data I want to get at a few nodes within the
structure.<xxxxx>xxxx</xxxxx>

if I run the following
=====
$xml = simplexml_load_file("./Sample.xml");
print_r($xml);
========
I come up empty.

But if I strip the soap wrappers, I can get at the data I want without
problem.

Is there a simple way to parse out the soap references or is the
another simple way to get at the data I want.?

How