Your strings are being escaped. Check out the docs on string literals:

The backslash () character is used to escape characters that otherwise have a special meaning, such as newline, backslash itself, or the quote character. String literals may optionally be prefixed with a letter r' orR'; such strings are called raw strings and use different rules for backslash escape sequences.

This is a historical usage dating from the early 60s. It allows you to enter characters that you're not otherwise able to enter from a standard keyboard. For example, if you type into the Python interpreter:

print "\xDC"

...you'll get Ü. In your case, you have \b - representing backspace - which Python displays in the \xhh form, where hh is the hexadecimal value for 08. \a is the escape sequence for the ASCII bell: try print "\a" with your sound on and you should hear a beep.

Escape sequence \a, \b is equivalnt to \x07, \x08.

>>> '\a'
'\x07'
>>> '\b'
'\x08'

You should escape \ itself to represent backslash literally:

>>> '\\a'
'\\a'
>>> '\\b'
'\\b'

or use raw string literals:

>>> r'\a'
'\\a'
>>> r'\b'
'\\b'