Replaced text with audio icon

[MaskedCarrot]

Explanation

Fixes #1845
Replaced audio language text with an icon

Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• The PR explanation includes the words "Fixes #bugnum: ..." (or "Fixes part of #bugnum" if the PR only partially fixes an issue).
• The PR follows the style guide.
• The PR does not contain any unnecessary auto-generated code from Android Studio.
• The PR is made from a branch that's not called "develop".
• The PR is made from a branch that is up-to-date with "develop".
• The PR's branch is based on "develop" and not on any other branch.
• The PR is assigned to an appropriate reviewer in both the Assignees and the Reviewers sections.

[oppiabot]

Hi! @MaskedCarrot, Welcome to Oppia! Please could you follow the instructions here to get started? You'll need to do this before we can accept your PR. I am closing this PR for now. Feel free to re-open it once you are done with the above instructions. Thanks!