The expected sound is the "WAIT!" voice, which you can clearly still hear. Anything in addition to that is of zero detriment to the accessibility of the system.

And you know this how? Because your gut tells you?

Because TFA includes videos with sound showing the actual crosswalk signals are present at before the "PSA" plays.

If "your gut" is a synonym for "the multiple videos in the actual article", then sure.

How is it impacted?