o_18tibebsk1upb80q14ejo8p12eva.pdf

More documents

Recommendations

Info

42 BoxofTlCE SPECIAL REPORT: Sound 1997 NOISES OFF Three Keys to Successful Digital Acoustics Digital sound in a theatre is great. That same digital sound seeping day this past summer, One I went to see "The Postman." I was very excited about viewing this poetic film, as it had recently won the Academy Award for best score. Much to my disappointment, I wound up watching this quiet art film while listening to most of "Independence Day," which was playing its multichannel discrete digital soundtrack in an adjacent auditorium. Although I was also looking forward to seeing "Independence Day," this was not my idea of a "two for one" screening pass. Whether onscreen or behind the screen, the latest development in sound technology—digital sound—does sell tickets. What are often neglected, however, are the acoustics ofthe space in which into the auditorium next door isn't. Three acoustic elements can make or break a digital sound environment. « this technology is to perform and its interrelation to the surrounding spaces. As we've all experienced, digital technology has significantly improved the sound quality of films over that of previous 35mm analog optical formats. Some of the digital capJibilities include discrete channels, extended lowfrequency response in the subwoofer and surround channels, improved dynamic range, and virtually unmeasurablc noise, wow and flutter. Many of these audio features approach (and some exceed) features previously available only with 7()mm SR release prints. Such A-Chain features combined with a B-Chain system designed to handle these capabilities bring the general audience much closer to hearing the film the way the director heard it in the mix room. But, in most cases. Incident Energy Figure By Marco d'Ambrosio ^ Reflected Energy ft X. \\ Absorbed Energy Transmitted Energy simply making the A-Qiain digital and installing more powerfiil loudspeakers and amplifiers won't make a theatre "digital ready." Most mix rooms have been designed with a great degree of consideration given to their acoustics—specifically, in how the various surfaces in the room absorb and reflect sound, how well the room is isolated from other rooms, and how much ambient noise is allowed into the room. It is these three interrelated acoustic factors (absorption, isolation, and background noise) that need to be addressed more critically in the constmction of theatres in this digital age. First, it's important to under- .stand the different ways sound 1. Sound energy can be reflected, absorbed or transmitted. ^^ ^e Uimsmitted. One way is for CINEMA SOUND 19 9 7 sound to create alternating waves of pressure in the air, as occurs with speech during a conversation or with music through a sound system. This is called airhome transmission, and it's the most common way people perceive sound. Another way is for a vibrating object to be connected, or acoustically coupled, to another object that in turn picks up the vibration and transmits it along to other objects that are also coupled. This is called structure-Ixmie transmission. If we are touching anything in this path, we can sense the vibrations. Also, at some or many points along the path, the air around the objects is alsoexcited, and we perceive this as airborne noise. In general, structure-borne noise issues tend to be more difficult lodail with than those that are solely aiitoome in nature.
This ABSORPTION is a complex physical property, which all surface materials in a theatre possess. In basic terms, absorption is the amount of airbome sound energy a material absorbs when that energy strikes the material. That trapped sound energy is actually dissipated within the material as heat. What isn't absorbed either reflects back into the theatre or passes completely through the material until it reaches another surface, as shown in Figure 1 on the previous page. That figure also exhibits how absorption and isolation are interrelated. It is also important to note that a material's absorptive quaUties actually vary with frequency, meaning that it could be a good Surface Mounted Panel Increase Thickness or Air Space HF Reflector or Diffuser away from its mounting surface or increasing its thickness will make it a better absorber at low frequencies. Placing a perforated or slotted facing in front of an absorptive panel will decrease absorption at higher frequencies, leaving absorption at lower frequencies unaffected. Also, under the careful design of an acoustical consultant, mned resonators or slot absorbers can be designed to absorb very specific frequency bands. See Figure 2, below. In relatively nontechnical terms, absorption is important in a theatre because it helps control reverberation (the overall decay of sound) and audible slap echoes either fk)m sidewaU to sidewall or from the screen to the projection wall. This is particularly important in theatres with digital playback frequency It s getting in the Thermal Stock For i4// Theatre Systems: • ICON • OMNITERM • BOCA • TICKET PRO • B.E.A.T. • MARS • GATEWAY • PACER/CATS • MARBLE • PRYSM • THEATRON Also ovailoble: Automoticketj, Roil Tickets, Custom-printed Souvenir Invitation Tickets, Coupon Books and Gift Certificates National TICKET C O.I P.O. Box 547 Shamokin, PA 17872 3C 9S] Call Our Customer Service Dept. 800-829-0829 • Fax 800-829-0888 International Dept. 717-672-2900 • International Fax 717-672-2999 Internet http://www.nafionalfickef.com Response No. 72 r Tuned Resonator Membrane Absorber Figure 2: A material's absorptive qualities vary with frequency, (d is the relationship between sound and its reflection.) absorber of high frequencies and a poor absorber of low frequencies (or vice versa). Thus, a material's absorptive qualities are measured across a wide frequency range (typically in octave bands) and listed as a table of coefficients of absorption, or ds. d is actually the mathematical relationship between sound energy that strikes the material and that which is reflected back; therefore, a material completely absorptive at a given frequency would have a 3 of 1 at that frequency, and a completely reflective material would have a 3 of 0. How a material is mounted will also affect its absorptive properties. In general, spacing a material systems, as pristine dialogue, exart stereo imaging of music and sound effects, and carefiil placement of stereo surround effects can be easily smeared by a theatre with inadequate absorption. Absorption within the theatre will also help reduce how much sound is transmitted to adjacent spaces. Although that isn't the primary purpose of absorption within a room, every little bit counts, especially when an exhibitor can have in excess of 1 1 3 decibels of subwoofer thumping away. Other important issues to consider when fitting a theatre with absorptive treatment, besides how much treatment, are where and how thick. A common contempo- THE BEST! Know who you deal with personally! One phone call gets the owner of America's best equipped shop and design lab. IDEAS to save tinne, money and difficulties. HADDEN r- THEATRE 10201 BunsenWay Louisville, KY 40299 (502) 499-0050 (502) 499-0052 FAX: Louis Bornwasser, Owner SUPPLY COMPANY Design-Consultation-Sales Response No. 40 January, 1997 43
Page 2 and 3: sents m%%l^. only $29 qe 'eryour ''
Page 4 and 5: DEPARTMENTS JANUARY, 1997 VOL. 133
Page 6 and 7: HOLLYWOOD UPDATES The Fighting Iris
Page 8 and 9: HOLLYWOOD REPORT LAURENCE FISHBURNE
Page 10: Cover THE BOXOFFICE INTERVIEW wnm P
Page 13 and 14: The Movies Just Keep Sounding Bette
Page 15 and 16: AN AMP IS AN AMP IS AN AMP.. unless
Page 17 and 18: . Response ighest rated soundwalls
Page 19 and 20: ... . laniiarv. 1997 19 123. Brent
Page 21 and 22: EQUIPMENT FOR MOTION PICTURE THEATE
Page 23 and 24: i o ^ :ri q: 9 ^ -s; < -2 - "^ '> &
Page 25 and 26: BoothAiitbmation I i I iSjt^stteijK
Page 27 and 28: Exploitips: Our Toronto-fest critic
Page 29 and 30: 9 Schrader and comedy—that ExplOi
Page 31 and 32: RGM INDUSTRIES 3342 Lillian Blvd. T
Page 33 and 34: ResDonse No. 196 ^^~KELMAR SYSTEMS
Page 35 and 36: IF YOUR THEATER IS A PLACE OF PEACE
Page 37 and 38: GEMMA RICHARDSON, VP, WORLDWIDE MAR
Page 39 and 40: After much (now legendary) experime
Page 41: 1 1997 This might be an especially
Page 45 and 46: Measurement of background noise in
Page 47 and 48: industry has used more creative des
Page 49 and 50: January, 1997 49 theatres. It's the
Page 51 and 52: Tootsie Roll's president and chief
Page 53 and 54: 8 Showmandiser Promotion of the Mon
Page 55 and 56: I — REVIEWS SPACE JAM •••l/
Page 57 and 58: — — REVIEWS WILLIAM SHAKESPEARE
Page 59 and 60: Innnarv 1Q07 ^Q NATIONAL NEWS DORAN
Page 61 and 62: ' found REGAL'S EXPANDING KINGDOM R
Page 63 and 64: Q&A: JACK VALENTI: AN AMERICAN IN P
Page 65 and 66: 1 Boxoffice Magazine presents Novie
Page 67 and 68: Dra . February March FEATURE CHART
Page 69 and 70: , New BOXOFFICE Independent Feature
Page 72 and 73: 72 Boxoffice . . Home ADVERTISER IN
Page 74 and 75: 74 BoxomcE The lEis IPicture Althou
Page 76: \^e will custom design and build yo

o_18tibebsk1upb80q14ejo8p12eva.pdf

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?