St. Bartholomew's Catholic Church in Katy, Texas, includes a fellowship hall with a great dome. Parishioners use the space for social events including meals and regular bingo games. High reverberation times in the fellowship hall reduced speech communication and acoustic comfort. Measurements were conducted to assess the reverberation time of the room before and after applying treatment to the space. Sabine reverberation time analysis was used to specify the recommended sound absorption for the fellowship hall. EASE analysis of the space reveals more interesting characteristics.
Parking Lot noise is regularly evaluated for CEQA noise assessments, but a standardized method has not been generally adopted. This paper presents sound level measurements of common parking lot activities. Other published sound level data for parking lot activities is provided to further solidify typical parking lot sound levels. A review of published methods for evaluating parking lot noise is summarized. The appropriateness of the methodology is evaluated and a simplified methodology is presented based on the similarities and differences applicable to California for CEQA analysis and the United States in general.
This presentation provides an overview and demonstration of some `classic' acoustic phenomena using a computer simulation. The computer program provides a visual rendering of an environment with a source and receiver. By allowing the user to vary some of the parameters of the environment, a user can see and hear the differences in spaces by changing the surroundings. The goal is to highlight the well known environmental factors that impact sound such as volume in a room. A variety of parameters and environments will be explored.
The design of laboratory animal vivaria should include consideration of factors that may impact the results of intended experiments. Two examples where the acoustic environment of birds could significantly affect experimental results include (1) song learning accuracy in isolated juvenile songbirds and (2) the preferences for bird songs by mates. We conducted a detailed analysis of a proposed vivarium design in a laboratory setting to assess important acoustical factors. We analyzed vivaria for room acoustics and sound isolation properties. Sound isolation and reverberation were primary concerns since bird song learning accuracy was an aim of the laboratory research. The environments are planned to be used to research juvenile birds learning a single model song during development. We tested the effects of treating the vivaria with sound absorbing foam, including the reverberation in enclosures and associated impacts on results comparing recorded bird songs. In addition, we tested the existing background sound levels observed in the laboratory and the sound isolation properties of the vivaria. Sound isolation results for the initial isolated environments shows transmission loss values from the exterior to the interior of the vivaria were significantly less than the expected 30 dB. Reverberation results reveal a distinct reduction when the interior of the vivarium enclosures were treated with a sound absorber.
A turbofan engine acoustic liner is effective at reducing propagated noise. However, there is room for improving performance or making the liner more compact. Plasma actuators have been shown to be useful flow control devices in a number of fluid flow situations. Combining the plasma actuator (PSJA) and passive liner technologies offers the promise that the attenuation of the acoustic liner can be improved with the addition of the active actuators. The research was divided into two realms: oscillatory flow and bias flow induced by the plasma actuator. A waveguide was constructed with a disturbance speaker at one end, an anechoic termination at the other end, and a mounting for Helmholtz resonators (HRs) in the middle. The PSJA technology was integrated into the neck of the a single HR. A single frequency, feed forward test was conducted to evaluate the oscillatory flow. This test showed that the implementation of the PSJA with a feed forward system could produce an additional 3 dB of attenuation. For this test arrangement the bias flow did not show any additional measurable attenuation. Interpretation of the results are discussed.
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