Add sound or other accessibility feature

[bkmgit]

Would enable people to have an option other than using visual feedback. Example libraries with audio captcha include

• https://gitee.com/chenhaohan88/captcha
• https://github.com/dchest/captcha It is also possible to add sound to a slider captcha. An example slider captcha is https://gitee.com/anji-plus/captcha

Happy to implement one of these.