The modern projector screens of today are highly specialized, intricate materials that require an immense amount of care and knowledge when matching projector-screen combinations.   In the interest of time I will limit this blog to only focus on aspect ratio, sight, and sound.
Aspect Ratio
Aspect ratio determines the overall shape of your screen and is calculated as follows:
Aspect Ratio = Width/Height
The result is expressed mathematically as x:y (more on this in a moment).  This resulting number is a critical component to your home theater experience and great care must be taken in selecting it.  The aspect ratio must be discussed in great length before researching brand names or specifications.  Since the beginning of movies, aspect ratios have evolved and vary greatly.  The most common aspect ratios (AR’s) are 4:3 (or 1.33:1), 16:9 (or 1.78:1), 1.85:1, 2.35:1, and 2.40:1.  But what do all these numbers mean?
4:3 (or 1.33:1) – The original 35mm silent film ratio. Today 4:3 is more commonly used.  The primary format used for the older CRT (cathode ray technology) televisions prior to the influx of HDTV’s (16:9).
16:9 (or 1.78:1) – The widescreen video standard.  All HDTV flat-panel televisions are 16:9.
1.85:1 – The theatrical video 35mm standard.  This standard applies to the US and UK.
2.35:1 – 35mm anamorphic prior to 1970, used by CinemaScope (or jus “Scope” was an anamorphic lens series used from 1953 to 1967 for shooting widescreen movies) and early Panavision (a motion picture equipment company specializing in cameras and lenses).
2.39:1 – 35mm anamorphic format from 1970 onwards.  Typically this numbers is rounded up and called 2.40:1.  This aspect ratio has been marketed to consumers as ultra-wide CinemaScope, Scope, or Panavision formats.
How does this all translate into the movies you’ll watch in your home theater to be?
Original Aspect Ratio (OAR) – this is the industry term used to refer to the original format a film was produced in.  For example, the movie Gladiator was released to movie theaters in 2.39:1 (CinemaScope format).  Gladiator was also converted to 1.33:1 (or 4:3) ratio to match the television standard at the time.
To demonstrate the impact aspect ratio has on your theatrical experience, I used a screen shot from the movie Terminator Salvation (2009) and formatted it in three of the most popular aspect ratios they are likely to be viewed in 2.35:1, 1.78:1 (16:9), and 1.33:1 (4:3).

The 2.35:1 Terminator Salvation as seen on a 2.35:1 Ultra-Wide CinemaScope HDTV projection screen WITH an anamorphic lens in place.  The ENTIRE image is viewable without any loss of information.  This is how the director intended you to see it.

The 2.35:1 Terminator Salvation as seen on a 2.35:1 Ultra-Wide CinemaScope HDTV projection screen WITHOUT an anamorphic lens.  In order to retain the full image black bars are present at the top and bottom.  The black bars on the left and right depict the area used when 2.35:1 Ultra-Wide CinemaScope screens are implemented.

The 2.35:1 Terminator Salvation as seen on a normal 16×9 (HDTV) screen.  You get the full image, but you still get the annoying black bars at the top on bottom.

The 2.35:1 Terminator Salvation cropped to fit a standard definition TV.  Notice how much information is lost.
The 2.35:1 CinemaScope format was introduced in the 1950’s when the growing popularity for televisions in the home increased so much that local cinema’s began hurting.  To combat the CRT television flying into homes across America, the movie studios needed to act quickly.  Their answer was to provide a truly unique experience that would provide a new and different emotion – the ultra-wide Cinemascope anamorphic screen experience.
Sound
There is nothing that compares to having your front left, front right, and center channel speakers directly behind the screen.  All sound effects and dialog come from directly behind the screen for one amazing knock-your-socks off experience.  But in order for sound to come through the screen there must be holes to let it through, and if there are holes then that must be light from the projector passing through the screen and that means pictures quality may be degraded.  But to what extend the degradation occurs is far more useful that a simple “yes it occurs.”  To investigate the matter we setup a test to measure at which point frequency rolloff occurs as a result of the sound first traveling through the screen before it reaches the theater audience.
For our tests, we are going to use the following components (only those relative to this article are listed):
132” Draper CinePerm 2.35:1 CinemaScope Format screen with Acoustical Transparency
Draper Series H Masking screen from 16:9 (1.78:1) to 2.35:1 CinemaScope morphing
Runco RS1100 Ultra White with CineWide AutoScope with a Large McKinley Anamorphic Lens
JBL Synthesis K2 9.4 Multichannel Cinema/Music System comprised of:
(1) SDP-40HD THX® Surround Processor/System Controller
(1) SDEC-4500P 12-Channel input/4-channel output, 256-band parametric EQ
(1) SDEC-4500X 16-Channel output expander for SDEC-4500 digital equalizer system
(1) S4500XLRIC Interconnect Kit
(10) S820 Stereo/Mono THX® Power Amplifier 800W Bridged Amplifiers
(3) K2 S9800SE-BG 3-Way, 15″ Floorstanding Loudspeakers
(4) S1S-EX 18″ THX® Passive Subwoofers
(6) S4Ai Vertical or Horizontal Multipolar Flush-Mount THX® Surround Loudspeakers

After extensive installation, setup, and calibration it was time to put the system through its paces.  We were only able to measure the slightest rolloff in the high frequencies above 8kHz.  Without a doubt, the benefits of having the center channel and front speakers positioned strategically right behind the screen far outweigh this small loss.  Another benefit is the more uniform soundstage across the three front channels by having the center channel speaker located at the same height as the fronts.  There is a level of unified, solid sound performance that occurs only in system designs that incorporate acoustically transparent screens.

Sight
Our screen material preference has always been smooth, natural-white surfaces.  Anything which deviates from that may affect the integrity of the image you see.  The result will in large part depend on how acute your vision is and your seating distance relative to the screen.  Seating in all twelve seats in the theater produced consistent results in regards to no noticeable video degradation.
To combat project light traveling through the acoustically transparent screen and then reflecting back onto the screen again (referred to as the moiré effect) was to implement a black scrim cloth.  A scrim is an acoustically transparent cloth that is used to block projector light from passing through but still allow sound form the speakers to reach the theater audience.   Without the scrim there is simply too much risk of reflections occurring behind the screen and therefore seriously hampering the integrity of the video image.  The scrim has an acclaimed 99% light blockage rate.  Initially we chuckled when we first heard this spec, but later we found it to be surprisingly right in the ball park.  However, to determine with greater certainty we would have needed much more sophisticated equipment than what we had available to us.
Summary
Pros:

• Film’s soundstage is dramatically improved
• Ability to match left, right, and center channel speakers thanks to behind-screen positioning
• Superlative acoustical transparency
• Unmatched acoustical performance compared to non-acoustically transparent designs
• Screen gain rivals that of traditional non-acoustically transparent screens

Cons:

• More expensive
• Calculations for viewing distance, screen type, projector type, and image brightness, become more critical to avoid visual artifacts from being introduced.

Final Notes:

• Do not select any system until both an 2.35:1 Ultra-Wide CinemeScope format and acoustically transparent screens have been thoroughly reviewed and considered.
• Hire a knowledgeable professional to design and install your system.
• Always plan out short- and long-term goals to make the best use of your time and budget.

For those of you just getting started, here is a list of screen manufactures (in alphabetical order):

• Da lite Screen Company
• dnp (Supernova Panorama)
• Dragonfly Screens
• Draper Projection Screens
• Elite Screens
• Planar
• Screen Excellence
• Screen Research
• Seymour AV
• Screen Innovations-also known as SI
• SmX Cinema Solutions
• Stewart Filmscreen
• Vutec Screens

Equipment:
JBL Synthesis is available from Quality Audio Video and Home Theater in Denver, CO as well as Runco video displays and projectors, Draper projection screens, and more.