Garrett Rauck | Assignment 5: Acoustics Reseach

I would urge everyone to check out this website:  http://lenardaudio.com/education/17_cinema_6.html. 
This is where I found most of my information, as it is extremely precise and informative. Awesome graphs and diagrams. Here are some of the things I discovered...

• The three 'R's' of acoustics are room Resonance, early Reflections, and Reververation (George Augspurger)
• Original large cinemas were modeled after opera houses. These opera houses used reverberation to amplify the musical sound to account for larger audiences. Mozart thought this was b.s. He felt that this excessive reverberation didn't accurately capture the sound he originally created and preferred outdoor venues.
• Side note: with art house cinemas, where the clientele is most likely cinematographic purists, it can be assumed that they would demand the same type of honesty out of their films that Mozart demanded of his music. Something to think about.
• The center speaker is mono and emits mostly dialogue in a film, while the left and right produce filler sounds in a surround-sound system. (See image below)
• Once again, it is likely that many (though not all) films showing at our theater will be older films and will have originally been played on a mono track. The purists will want this honesty, so surround sound may not be the way to go for those films.

• #slapechoes == bad  -> True
• decrease intelligibility (acoustic legibility)
• Echoes repeat past sounds while interfering with new sounds, which creates a vicious cycle of impure sound and "DESTRUCTIVELY CHANGING WHAT WE ARE HEARING FROM WHAT THE DIRECTOR INTENDED.
• The amount of time for reverberation to diminish to -60dB (or 1/1,000,000 of its original energy) is called Reverberation Time (RT or T60) (See image below)

• Those red pleated curtains on the inside of multiplex theaters absorb high frequencies, while having little effect on low frequencies. The seats and audience also absorb sound. Speaking of seats: Why the Epidaurus Theatre Has Such Amazing Acoustics
• There are different acoustic characteristics depending on the size of the theater. The time that sound has between being reverberated/absorbed by one wall and rvrbrtd/absrbd by the next wall is called the 'Mean free time' or 'Mean free path'. This time is shorter in smaller theaters and the sound will thus be rvrbrtd/absrbd more frequently. (below)

• Bass frequencies have long wavelengths. Due to propagation directivity, the inverse square law does not apply in SMALL CINEMAS. In other words, the theater is too small for the bass to dissipate as it normally does. The result is a longer-lasting base wave, I believe...?
• CRITICAL DISTANCE: 'THE MANAGEMENT OF ACOUSTICS FOR ENTERTAINMENT VENUES REQUIRES UNDERSTANDING CRITICAL DISTANCE.' critical distance is where the direct sound from the speakers and reverberant sound energies are equal. Increasing room reverberance == closer critical distance, vice versa

This website is packed full with info, so I'm not going to put it all here... I'll let you all fill yourselves in.
(LINK AT TOP)

Cheers.

G