UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36

Example URL:
https://www.youtube.com/watch?v=spwyGQuIXwc

Steps to reproduce the problem:
1. WIth sound enabled, play a video with audio on any web site.
2. Notice that while the video might sound good for a few seconds at first, the audio quality becomes muffled and degraded suddenly after a few seconds.
3. Notice that in subsequent audio playback / streaming operations, the audio quality remains degraded.
4. Notice that playing audio through iTunes or any other audio application does not have the same problem so it seem to be specific to the chrome browser.
5. Notice that changing the value of the audio playback native sample rate using the Audio MIDI Setup utility temporarily makes the problem go away, so that chrome will again sound good for the first few seconds of audio playback, but will again degrade in quality after a few seconds.

What is the expected behavior?
Audio sounds correct all the time in chrome.

What went wrong?
Audio starts out sounding OK sometimes, but after a few seconds sounds muffled, lacking treble frequencies.

Did this work before? Yes unknown

Is it a problem with Flash or HTML5? N/A

Does this work in other browsers? N/A

Chrome version: 67.0.3396.99  Channel: stable
OS Version: OS X 10.13.5
Flash Version: 

Contents of chrome://gpu: 

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