Starring: Captain John Sheridan, Commander Susan Ivanova, baryon density
This movie keeps the total matter density constant, but increases
the fraction of ordinary matter, baryons (see the two dials shift in sync).
Density oscillations caused by the competition between pressure
and gravity in the early Universe give
rise to wiggles "acoustic peaks") in both the CMB and galaxy power
spectra - the more baryons, roughly speaking.
Hower, it's actually mainly the odd-numbered peaks (1, 3, etc) that get
helps distinguish baryons from
cold dark matter.
Indeed, you can see that the 2nd peak actually shrinks
for a while. This is why the Boomerang and Maxima measurements prefer
lots of baryons - they don't see much of a 2nd peak.
For more details on the baryon effect, see
Note that both the CMB and galaxy fluctuations are unaffected on the
largest (leftmost) scales. Moreover, note that the
galaxy power spectrum doesn't merely get wigglier, but
gets suppressed as well.