Per a 14 September post on Google's Chromium Blog (see Read External Article, below) Chrome 63 (coming in October) will give users the option to disable audio for individual sites, and Chrome 64 (January 2018) will permit autoplay only when video contains no sound, or user chooses to let the video play.

With those changes, behavior of Chrome will be more consistent across devices than it is now.

Latest update to Google's Autoplay Policy says:

Under the new policy media content will be allowed to autoplay under the following conditions:

• The content is muted, or does not include any audio (video only)
• The user tapped or clicked somewhere on the site during the browsing session
• On mobile, if the site has been added to the Home Screen by the user
• On desktop, if the user has frequently played media on the site, according to the Media Engagement Index

Obviously these changes have implications for advertising.

According to NetMarketShare, Chrome has about a 57% browser share for both desktops and mobile devices. So this is important.

Ad-attention research on YouTube ads done by Nielsen and Ipsos for Google earlier this year found that "2.4X attention was paid to ads with full sight and sound vs. ads shown with audio off and subtitles."

And based on that research, Google published the conclusion that "users who both see and hear ads experience higher brand awareness, higher ad recall, and higher brand consideration, vs. those who only see or only hear ads."

(But, on the other hand, note that recent research by Twitter found that "Presence/absence of sound seems not to be a factor in the effectiveness of Twitter videos.")

Could differences bertween YouTube and Twitter as video ad platforms account for this? Would be interesting to see some research on that question.

Advertisers now using video ads with sound need to find ways to get users to allow their ads to run with sound, and/or get more clever about making silent ads.