[paddington]

HF roll off isn't necessarily indicative of lossy data compression.

Some MP3 encoding schema will do a low pass filter as part of cutting data, but not all. It just isn't a good way to determine if the audio has been through a lossy compression algorithm.

To tell for sure, you need a real spectrum analyzer that will show you the aliasing that happens with lossy compression. There are plenty threads here in the help forums with examples.

Let's look at your two samples:

Generally, using Adobe Audition or Cool Edit Pro 2.0+, you'll want to examine a 2 sec slice of audio to see if aliasing is present.


1st one, "track 10"

This could be an FM broadcast. They roll off around 15kHz in the US FM stereo system. The energy shown above that could be harmonics or just reception noise. There's some popping evident, which could be coming from a variety of things.

Someone transferred this with an analog cable, near a CRT with the flyback running at 15.734 kHz (NTSC spec). You can see that in the spectrum. It bled in.

1st one is a lossless recording.









2nd one, "Icehouse08"


This one is lossy. For sure. Looks like MP3. You can see the chunks of data missing and hear the edges of the holes, when listening. This is what the 'glassy' effect of lossy audio sounds like. It's not bad MP3 but it is certainly noticeable, to me, when listening.

You can sort of see these blockies with the spectrum you posted but it's much more evident with the spectrum analyzer in the Adobe apps.