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IMPROVEMENT OF THROUGH-WALL AIR CONDITIONER TRANSMISSION LOSS Chad N. HIMMEL, P.E. JEACOUSTICS, Engineered Vibration Acoustic & Noise Solutions 1705 West Koenig Lane, Austin, Texas 78756, USA SUMMARY Packaged Terminal Air Conditioners are often called "through-wall" air conditioners since they are usually installed in a sleeve passing through the exterior building wall. While through-wall air conditioners generate their own noise with internal fans and compressors, they also tend to allow unwanted outside noise to pass through the unit to interior spaces. This paper compares field-tested sound data for fan and compressor noise of six different models and describes how a sound baffle was designed and successfully implemented at a hotel, using standard building materials to reduce noise transmission through a through-wall air conditioner. INTRODUCTION A large hotel chain planned a new building for a site between an active railroad and a 6-lane freeway. Through-wall air conditioning units would be installed in each hotel room, through sleeves in exterior walls. Noise concerns included air conditioner noise and intrusions of truck and train noise through exterior walls and windows into guest rooms. Fans, compressors, and airflow through ducts and grilles in air conditioners would generate noise when operating, and the through-wall penetrations would allow unwanted noise outdoors to pass through the equipment to interior spaces. The hotel owner retained acoustical consultants to provide sound control recommendations for exterior walls and air conditioners. Exterior wall designs were improved and exterior windows would include storm windows to help reduce outdoor-indoor sound transmission. Therefore, the air conditioner was expected to become the primary path for outdoor-indoor noise transmission. -
Analysis of the Factors Affecting Noise in Schools Using Experimental Design
International Journal of Scientific and Technological Research www.iiste.org ISSN 2422-8702 (Online), DOI: 10.7176/JSTR/5-5-06 Vol.5, No.5, 2019 Analysis of the Factors Affecting Noise in Schools Using Experimental Design Ali Yurdun Orbak (Corresponding author) Industrial Engineering Department, Bursa Uludag University Gorukle, 16059, Bursa, Turkey E-mail: [email protected] Fikret Umut Aydin School of Natural and Applied Sciences, Bursa Uludag University Gorukle, 16059, Bursa, Turkey E-mail: [email protected] The research is financed by TUBITAK (The Scientific and Technological Research Council of Turkey) Project No. 114K738, Noise Pollution at School: Causes, Effects and Control (Sponsoring information) Abstract Sounds that are high enough to negatively affect our perceiving are called noise. Noise adversely affects students’ success. The term (four different terms), the time when the noise measurement is taken (during courses or breaks), and location (corridor or classroom) are usually considered as main reasons of noise in schools. In this study, noise measurements are collected in several of Bursa’s primary and secondary schools and factors which affect noise significantly are investigated. To analyze the data, general full factorial experimental design with four factors (term, time, location and school) is constructed. MINITAB 17 and Brüel & Kjaer Measurement Partner Suite programs are used for data analysis. Analysis results indicate that noise values exceed the limit values set by the World Health Organization (WHO) and also noise regulations currently in effect in Turkey. According to the experimental design results, for secondary schools, the school which has partial acoustic insulation, is less noisy than the school which doesn’t have any acoustic insulation. -
April 1971 5
THE SOUND ENGINEERING MAGAZINE April 1971 5, A Modular Console Design Studio Construction Techniques Low -Frequency Sound Absorbers Complete Guide to the West-Coast AES Convention U u1 www.americanradiohistory.com Turn on the Ampex AG-440B and listen: tape tension. Easy changeover from quarter - Perfect silence. inch to half -inch tape. The AG -4408 is also one the Switch to record: no pop. of most versatile recorders you can buy. Console. Portable. Or Hit the stop: no pop. rack installation. Start with one channel. Build up to four or more. It's Go from rewind to stop: no tape shrieking. the perfect reproducer for the future four channel stereo. The Ampex AG -440B is so mechanically quiet To hear other quiet reasons why the AG -440B some engineers use it in the same room with can be your best recorder /reproducer buy, and live microphones. It's so electronically quiet how you can put it to work for you for as little you can forget about switching pops. as $50 a month, give us a call. (415) 367 -4400. That's why, in its own quiet way, the AG -440B Or write Ampex Corporation, Professional Audio has become the standard of excellence. Division, M.S. 7 -13, Redwood City, Calif. 94063. Ampex quality is featured throughout: Rigid die - cast frame. Modular design with front -mounted circuit boards. Individual torque motors control AMPEX Ampex creates perfect silence. MEW The Ampex AG -4408 recorder /reproducer. See us at the A.E.S. Show, May 4 -7, Los Angeles Hilton (Booth 92 -96) (.i)rlr lll r)rr lir'urlrr 1r (:inrl www.americanradiohistory.com coming \oxt Month A most vital subject to audio pio- fessionals everywhere is the topic of a multi -part article beginning next month.