<p>We have a database that many persons have to have access to. I am looking for a way that will allow us to get notification whenever "alter" occurs on this database, so other parties can be aware of it. Please advise.</p>

Many persons should NOT have ALTER permission on a production database - very few people should have ALTER permission on a production database.  Actually, you probably shouldn't have many people empowered to make changes in test databases, either.
You can consider whether auditing is the correct solution - in some DBMS, it would be one way of detecting changes, but alerting would be harder (other than by some variation on the theme of 'grepping the audit log').  There may be other ways in Oracle.