Do you want to be able to listen more effectively and for longer periods?
Many halls and gathering spaces actually work against you hearing clear and clean sound. You might think it is a difficult problem to fix but actually it is quite simple.
It's about hearing the sound direct from the source, not the reflected sound. When your having trouble hearing most often it is because you're hearing both the direct sound and several reflections of the sound.
What happens when you get several images of the same sound arriving at different times? Your brain has to work hard to take these images and put them back to one image. It's a lot of work and you can only do it for awhile. Then what happens? You tune out, your brain shuts down and you end up looking at the chandelier!
Hear the Difference absorbing Echo can make on a typical hall
Designing Better Rooms and Fixing the Rest
As mentioned above conference rooms can be fixed and meeting rooms can also be designed to not have echo issues. At the simplest level it is about adding soft cushy sound absorbing materials to a space so that sound can not bounce back at you but instead gets eaten up by sound trapping materials.
The selection of materials is about the location of the material, the efficiency of the material i.e. its ability to absorb and trap sound, and it's asthetic appeal. Acoustic materials are rated and if you read closely in the ceiling tile isle at Home Depot you will see that most are rated at about 0.6, the panels shown above are rated at about a 1.1. I am not going to get into all the complex calculations but you shoud be aware that a panel that is 54% as efficient as another means you will require more surface area.
You might also note that different thickness of panels and density does mean that some panels can trap different frequencies better. So a 2 and a 3 inch panel can trap lower frequency sound that a 5/8 inch ceiling tile can't.
There are really two things that are worth noting in sound panel placement before you set the architects and room designers in motion. Picture yourself sitting or standing in the space doing what the room is supposed to be used for. Now envision mirrors on the wall surfaces. In the case of a PA system think about where you might see the reflection of the speaker on a wall. These are the places to treat with sound abatement.
The second is that sound piles up in the corners of rooms. Try walking into the corner of a noisy room or restaurant and see what sound you are getting at about 1-2 meters from the corner. This too should be treated if not you might steer to a different table in the restaurant!