It's not just visually-impared users you should be considering here. Think of users who only use keyboard, or have broken their wrist, or all sorts of users. Accessibility ≠ only blind users.
But anyway, to answer your question - you have a text field in your first example. That is the approach to take. The slider should be an enhancement to the form, it shouldn't be the only input method.
Provide fields whose value is linked to the slider (sliding the thumb changes the value in the field) and vica-versa (typing in the field moves the thumb too). Give those fields proper labels; if not visually definately in the markup itself, so that the users know what they are for (i.e. 'maximum value' + 'minimum value') and provide on-screen text and feedback explaining the rules of the fields, and you should be fine.
That will cover the screen-reader issue (marking up your HTML using correct standards is almost always all that is needed to be screen-reader compliant) and will make it usable for persons not using a mouse as well.
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