Did I blow my Speaker after playing a 22 kHz tone?

Is my sweet late 2016 (27'') iMac speakers gone!

Well... I played 22 kHz tone and... Seconds later my speakers sounded (muffled) like missing the Treble and slight on midrange... only Bass with hint of Midrange!

Speakers sounds just muffled which is like hearing the neighbor speakers, better yet description it's exactly when you hear someone on phone speakers, exactly clear but still phone speaker, like, no (Treble) even in startup.

...and any suggestion on what really happen to my iMac speakers would be appreciated.

Software-wise check:

• Driver is working because the jack audio (3.5mm) works just fine when o plug my EarPods.
• Did a hard reset.
• Checked on MIDI audio setup setting, and reconfigurations nothing strange

Hardware-wise, I haven't a clue!

--Noticed: That if i'm playing anything else, and play the file again it would cancel (can't hear) the other sound, even if it's coming from a browser!

Wish to at least troubleshoot this problem

-Thanks in advance