IPhone :: How To Make Text Message Notification Work Without Quitting The App

in the text message conversation view,there's only a soft sound alert when new messages are received.even when the screen is off, you get no popup preview or a regular notification sound whatsoever.the only way to keep getting the regular notification & previews is to quit the app each time you send out a text.often times when you are in the middle of something and are unable to focus on the phone itself for the conversation, you forget to quit the message app, then you are totally not aware there have been messages coming in because it only gives you a soft sound alert that's totally unable to hear when you're outside walking, or other similar scenarios

It's been bugging me for years, it's specially annoying when the other person I chat with isn't aware of this issue and ocassionally misses out my messages.i mean,if apple insists that to avoid this problem, the users MUST remember to quit the conversation RIGHT AFTER EVERY SINGLE LINE, this is just absolutely unrealistic.I now do it every time because I'm aware of the issue, but not the other people I have conversations with.I've had too many situations where I had to wait for a long time to receive response only to find out that the other person wasn't aware the new text messages, because it was simply too soft to hear, and completely no other sort of things to notify you with.so i wonder if there really isn't a way to change the notification behavior, cuz apparently it's impossible that I make everybody I send text to change their habits just for this.

Info:
MacBook
Pro, Mac OS X (10.7.2)