Meeting Topic: Tour of Riverbank Acoustical Laboratories
Speaker Name: Eric Wolfram, Laboratory Manager, RAL
Meeting Location: 1512 S. Batavia Avenue, Geneva, IL 60134
The Chicago section toured Riverbank Acoustical Laboratories in Geneva, IL. Laboratory manager Eric Wolfram presented a slide show on the history of the research facility. The presentation covered the diverse and obscure scientific pursuits of the lab's wealthy founder Colonel George Fabyan which included cryptography and acoustic levitation. Fabyan's hiring of Dr. Wallace Sabine, an acoustic researcher from Harvard University, led to the construction of an acoustic test room in 1918. This was the first independent lab for the purpose of studying architectural acoustics, specifically sound absorption. The same lab is still used to this day for making diffuse field measurements various of materials and construction. The lab does acoustic characterizations for international clients following rigorous standards.
Following the presentation, Eric and test engineer, Miles Possing, provided attendees with a tour of the facility including Dr. Sabine's lab. There we were able to experience the long reverb time of the diffuse field room. Rotating panels suspended from the ceiling help create a diffuse field and the sound pressure level is measured using a reference microphone on a rotating stand. Often large samples or specimens such as door frames and walls must be constructed and prepared in the workshop or in the room itself. An explanation was given of the preparation and methods for making incredibly accurate measurements for absorption coefficients and transmission loss. Eric and Miles discussed the American Society of Testing Materials (ASTM) standards that pertain to the acoustical characterization of various construction materials that they are required to test. One test involves using a tapping machine to simulate the impact of hard shoes and quantify the isolation of the floor surface. The meeting concluded with a session of questions.
Written By: Chris Bradt