Shooting Range Acoustic Consulting & Noise Control

Shooting Range Acoustic Consulting & Noise Control

Shooting Range Noise Sound transmission from gun ranges has become a growing concern as shooting sports increase in popularity, and firing ranges are built in close proximity to retail areas and residential districts. We work with developers, architects, engineers, and city planners to evaluate potential noise concerns from shooting facilities. Wave Engineering, Inc. evaluates new and existing ranges with computer modeling and on site sound measurements, and can assist with exterior noise, permitting, and compliance with state and local noise codes and ordinances. We can also recommend acoustic treatments to control noise and reverberation inside the range, retail, and classroom areas. For more information, please watch our video profile on gun range noise and acoustics, below… HVAC systems shown in this video are by Carey’s Small Arms Range Ventilation. To Get Help With Your Shooting Range Project Contact Us...
Are Your Video Conference Room Acoustics HD-Compatible? (Part Two)

Are Your Video Conference Room Acoustics HD-Compatible? (Part Two)

In a previous post, we discussed ways that the acoustics of a conference room can affect the audio quality of the video conferencing system. Here in Part 2 we will go over some general recommendations on designing the room to get the best sound from the system. Good Design Principles The three main pillars to good acoustical design for a video conference room are: 1. Low background noise 2. Low reverberation 3. Microphones located close to the talkers If you can provide those three items in all conference rooms, you can achieve the natural, immersive sound quality that your HD video conference system is capable of. Background noise The HVAC noise in the conference room should be less than 30 dBA or Noise Criteria (NC) 25. Most building HVAC systems will exceed this level unless care is taken to add lined duct, locate equipment away from the room, and use low air velocities. Many conference rooms have a glass wall looking outside or into a corridor or lobby area. Intruding noises like traffic or people talking outside the room can interfere with the conference too. Some conference areas are not even divided from the rest of the open office area, which is not a good idea for video conferencing. Reverberation An ideal conference room should have a reverberation time around 0.5 seconds. This is not possible in a room with a lot of hard surfaces like glass, drywall, concrete, or exposed metal deck. A reverberant room makes speech sound muddy and makes the background noise louder. Soft, sound absorbing materials are needed to control reverberation, and they should be...
Are Your Video Conference Room Acoustics HD-Compatible?

Are Your Video Conference Room Acoustics HD-Compatible?

There are many market factors driving the growth of video conferencing, and manufacturers like Polycom and ClearOne have responded with better technology. These modern video conference systems offer bigger displays, higher resolution video, high definition audio quality, integration with mobile apps, and so on. However, if this advanced technology is installed in a poorly designed conference room, the results can be disappointing. A good conference room design and system installation takes into many factors, including lighting, background color and patterns, camera and video display locations, microphone and loudspeaker type and placement, background noise, and room acoustics. This post will focus on ways that the room design can enhance or reduce the audio quality of the system. A follow-up post will provide more detail on good room design principles to get the best audio quality possible out of any videoconferencing system. The advent of HD audio quality Traditional video and teleconferencing systems relied on telephone connections for communication, which inherently limited the audio quality. For example, landline phones are filtered to a narrow range of frequencies that are most important to speech intelligibility. As a result, voices can still be understood, but they don’t sound as natural as they would if you were in the same room with the person. Compare these two audio files to see if you can hear the difference in quality: unfiltered audio  audio with telephone filter As we move away from landlines to cell phones and VOIP systems, there are other ways that audio quality can be compromised. High quality digital audio requires a lot of data and causes network congestion. Phone systems try to...
Sound Masking for Speech Privacy

Sound Masking for Speech Privacy

Many open office areas employ electronic sound masking systems to create an even distribution of background noise that is just loud enough to help mask distracting noises (particularly from other conversations) without being loud enough to be a nuisance. The system typically consists of special loudspeakers mounted in or above the ceiling and a head-end unit that generates and shapes the noise. Another useful application of sound masking is to improve speech privacy between rooms. Privacy is traditionally assessed simply by using the Sound Transmission Class (STC) of the partition between two rooms. However, this is only part of the picture. Privacy is dictated both by how much sound passes through the partition (STC) and the background noise level in the receiving room. Obviously, it is easier to eavesdrop on a conversation if the receiving room is quiet. There are many situations where privacy is important and the background noise level can be used to our advantage. Speech privacy is important in healthcare where HIPAA requires that “reasonable safeguards” be taken to protect the privacy of patients’ personal healthcare information. The 2014 FGI Guidelines for Hospitals and Outpatient Facilities acknowledges the effect of background noise on privacy in the STC requirements between Exam Rooms. Table 1.2-6 requires STC 50 between Exam Rooms unless there is an electronic masking system, in which case only STC 40 is required. A 10-point difference in the STC rating is significant, and it may be less expensive to build STC 40 walls and install a sound masking system in an exam area than to build STC 50 walls and no masking. Sound masking can...
Beware the Gypsum Association Manual STC Ratings

Beware the Gypsum Association Manual STC Ratings

Do you select Sound Transmission Class ratings from the Gypsum Association Fire Resistance Design Manual? The GA manual contains a lot of good information on fire and sound ratings. The sound ratings, however, must be used carefully. Knowledgeable acoustic consultants do not rely on the GA manual Sound Transmission Class ratings, but use laboratory test reports (multiple reports when available). We may also supplement the lab test reports with field test reports and calculations. Our goal is to determine the most likely average rating for a wall or floor-ceiling. STC tests, even in a laboratory, are not perfectly repeatable. The same wall can be tested in five different labs with five different results. The same wall can be tested multiple times in the same lab and yield different results. Wall construction isn’t perfect and the test method isn’t perfect. Multiple tests of the same wall usually follow more or less a bell curve distribution.     The Gypsum Association categorizes a partition based on one lab test result. The GA categories are typically STC 45-49, 50-54, 55-59, etc. The STC range given by GA is not the range of STC test results for a particular wall. It is simply the category that GA has assigned that wall to. GA gives no indication whether a particular wall falls at the low or high end of that category and a 5-point difference in STC ratings is significant. Unless you research and find the specific lab test referenced by Gypsum Association, you won’t know if your wall’s test is at the high end or the low end of the GA category. Partitions...