Sound deteriorating in Fedora 32 beta

[tomitek]

Description of problem:
While playing any music (for example with Rhythmbox app), opening Firefox Web browser (v. 74.0) with this add-on enabled causes sound to deteriorate dramatically.

Version-Release number of selected component (if applicable):
Fedora 32 beta
Linux Kernel 5.6.0-0.rc5.git0.2.fc32.x86_64
Firefox v. 74.0
TTSFox v. 0.0.28

How reproducible:

Steps to Reproduce:

1. Play any music with Rhytmbox or "Filmy" app (Polish for "Movies" app)
2. Sound is crystal clear.
3. Open Firefox Web browser with TTSFox add-on enabled
4. Sound will degrade dramatically
5. Close Firefox
6. Sound will be crystal clear again after few seconds.

Actual results:
As described above

Expected results:
No sound deterioration while opening Firefox browser.

Additional info:
Procesor: AMD Ryzen 5 3600
Motherboard: MSI MPG X570 GAMING PLUS
Graphics card: MSI Radeon RX 5700 8GB GDDR6

In Fedora system settings, sound output device is "HDMI / DisplayPort 5 - Navi 10 HDMI Audio". Actually sound is played by speakers in Philips 436M6VBPAB/00 Monitor connected via DisplayPort cable.

[tomitek]

The same problem is in Ubuntu 20.04