Consider

auditory nerve

• : pertaining to, or affecting the auditory nerves or the sense of hearing.

• oriented to or relying heavily on the faculty of hearing.

Auricular :

• Of or relating to the sense of hearing or the organs of hearing.
• Perceived by the tongue: an auricular confession.

What should one look for in a book about the universe?

Consider

auditory nerve

• : pertaining to, or affecting the auditory nerves or the sense of hearing.

• oriented to or relying heavily on the faculty of hearing.

Auricular :

• Of or relating to the sense of hearing or the organs of hearing.
• Perceived by the tongue: an auricular confession.

What should one look for in a book about the universe?

Consider

auditory nerve

• : pertaining to, or affecting the auditory nerves or the sense of hearing.

• oriented to or relying heavily on the faculty of hearing.

Auricular :

• Of or relating to the sense of hearing or the organs of hearing.
• Perceived by the tongue: an auricular confession.

What should one look for in a book about the universe?

Consider

auditory nerve

• : pertaining to, or affecting the auditory nerves or the sense of hearing.

• oriented to or relying heavily on the faculty of hearing.

Auricular :

• Of or relating to the sense of hearing or the organs of hearing.
• Perceived by the tongue: an auricular confession.

What should one look for in a book about the universe?

You could use integral

of or belonging as an essential part of the whole; necessary to completeness; constituent: an integral part.

What other factors are involved in the economic recovery of Russia?