Automatically notify the customer they can use speech to text for comment boxes in mobile surveys

Most customers take their surveys' on their mobile devices. It is proven to improve customer comments when we tell the user they can use speech to text.

There was a study done by my current boss that tested this theory. They had a simple one liner that said "feel free to use speech to text here" (Siri, etc. ). My boss did a before and after and there was a DRAMATIC improvement on the amount of comments and people finishing the survey.

If there is a way for Gainsight to recognize that the survey is being taken on a mobile device it would be best practice to add some text in there for comment boxes letting the user know they can use speech to text. 
This would be a major improvement if the quality of the speech to text was at least as good as the siri standard. My fear would be if lacking, the quality of feedback may prove less helpful.