The one that surprised me the most was the inability to replay music in your head. Probably because I do that a lot.<p>Here&#x27;s a series of things you could try.<p>- Sing &quot;Twinkle Twinkle Little Star&quot; out loud.<p>- Do it again silently -- don&#x27;t vocalize -- but keep moving your mouth, lips and tongue. If you&#x27;re like me, you&#x27;ll also still feel your throat and vocal chords moving.<p>- Do it again silently, without moving your lips, but still move your tongue and vocal chords.<p>- Do it again silently, but keep your tongue still, just move your vocal chords silently.<p>- Do it again, entirely silently, in your head.<p>I&#x27;d be interested to learn which steps are hard for you. When I&#x27;m singing a song &quot;in my head&quot; I&#x27;m actually doing any one of the latter three actions.<p>Relatedly, when I&#x27;m talking to myself in my head -- which I do often, usually while reliving an old conversation or anticipating a new one -- I often do the throat and tongue motions. Occasionally I even do the mouth motions, which is a good way to get people to look at you strangely :)