Tuesday, February 15, 2022

Smart Phone or Sound Level Meter?

Jonathan Chui, Stantec Consulting
Justin Dos Ramos, Nureva Inc.

In 2022, most people in Canada have a smartphone.  Since smartphones have built-in microphones, electronics and processing, downloading of a free or low-cost application is all that is needed to turn them into a sound level meter.  However, are smartphones accurate enough to replace traditional ANSI Type 1 or 2 sound level meters?

Kardous and Shaw (2014) investigated the suitability of smartphone apps for occupational noise measurements. They studied a sample of smartphones and tablets with 4 Apple devices, 10 iOS apps, 5 Android devices and 4 Android apps. Measurements were conducted in a diffuse sound field in a reverberant noise chamber. Seven levels of broadband noise, ranging from 65 to 95 dB in 5 dB increments, were set as reference measurements and validated by calibrated measurement systems, including a Type 1 sound level meter. In total, over 1680 smartphone measurements were analyzed. Measurement results from four iOS apps showed mean differences within ±2 dB/dBA. This is good enough for ANSI Type 2 and Occupational Safety and Health Administration (OSHA) standards and suggests that certain apps for Apple smart phones and tablets may be considered reliable and accurate for use in occupational noise measurements. On the other hand, the Android-based apps did not offer the functionality and accuracy needed for occupational noise assessments.

Murphy and King (2016) did extensive testing of 100 smartphones, including 65 iOS-based devices (7 models) and 35 Android-based devices (18 models) to assess their suitability for environmental noise measurements. Four iOS and three Android apps were tested. In total, there were 1472 tests. Measurements were conducted similarly to Kardous and Shaw, but reference noise levels were set at 50/70/90 dBA. The background sound level in the room was 27 dBA.

Android devices had much higher variability in comparison to iOS devices. Different hardware used in the variety of Android devices is likely a big factor. Overall, Android devices under-measured levels while Apple devices over-measured levels and offered significantly better measurement consistency and reliability.  Newer phones were also more accurate, but it was unknown whether they are equipped with better microphones or the older phone microphones deteriorate over time. In general, though, smartphones were more accurate at middle of the road noise levels of 50/70 dBA in comparison to the lowest (background only at 27 dBA) and highest (90 dBA) noise levels. This suggests smartphones may not be suitable for some ambient, background noise or hazardous noise level measurement uses. The conclusion was that smartphone apps on the whole are not quite ready to replace traditional SLMs, but a combination of good hardware and software can produce a smartphone that accurately measures sound level.

A more recent paper by Shahnaz and Brown (2020) compared the accuracy of smartphone apps from both Android and iOS devices to a Type 1 sound meter in real world environments (living room, classroom, restaurant, nightclub, public transit, and a fitness class).  The results indicated a variation of 3 dB or greater between the apps and the sound meter were common. They concluded that these apps should not be relied on as an accurate tool to determine hearing protection measures because of the amount of inconsistency between apps and devices. However, the smartphone apps are good for providing a general idea of the sound level in any environment.

Smartphones with external microphones and apps that allow calibration of the sound level were not considered. These would not likely be used by the general public. The combination of hardware and apps result in a wide range of deviations in measurement results.  A singular smartphone measurement is most likely not a reliable indicator of a true noise level, but a large set of these measurements may converge to the true noise level. 

New smartphone models and apps are introduced yearly, and overall sound measurement accuracy and reliability could improve in the future.  Smartphones are ubiquitous tools that can provide useful general noise information. They are a convenient means to explore everyday acoustic environments and open up the potential of large, crowd-sourced sound databases. However, they should not be considered a replacement for a purpose-built sound level meter when precise and reliable measurements are required in a sound assessment.

References

C. Kardous and P. Shaw, “Evaluation of smartphone sound measurement applications”, Journal of the Acoustic Society of America, 135, 186-92, (2014).

E. Murphy and E. King, “Testing the accuracy of smartphones and sound level meter applications for measuring environmental noise”, Applied Acoustics, 106, 16-22, (2016).

N. Shahnaz and S. Brown, “How accurate are these smartphone sound measurement apps?” Canadian Audiologist, 7, (2020). 

Jonathan Chui, PEng, INCE is a Senior Associate, Team Lead in the Noise Management Group at Stantec Consulting.

Justin Dos Ramos, CET is with Nureva Inc.

Saturday, February 12, 2022

Update on Stopping Train Whistles through the Banff Townsite

Richard Patching, PEng, MEng


Some residents of Banff have petitioned the town council to restrict or eliminate the sounding of train whistles in the vicinity of the town. This was reported by the Rocky Mountain Outlook on March 29, 2021 and on Global News on April 8, 2021, after the presentation of a delegation on March 22nd.

AANViS reported in a previous post that during the May 10th meeting of the Town Council, the council passed a motion to have the Town’s Administration consult “with the railroad operator on the feasibility of creating a railway quiet zone along the railway corridor in the vicinity of Banff, and report back to Council before the end of Q3 2021.”

The Town of Banff is the road authority for the railway crossing at Norquay Road, but Parks Canada is the authority for the crossing at Compound Road northeast of the main townsite. Based on an e-mail from CP to the town (November 17th, 2021), the Town would have to hire an engineering firm to conduct a compliance audit to meet all standards for the Norquay Road crossing. The member of the public who made the original request for the quiet zone (aka whistle cessation) would need to engage Parks Canada for the Compound Road crossing.

There have been long-running discussions involving CP, the Town and Parks Canada concerning illegal pedestrian rail trespassing near the industrial area between Compound Road and Norquay Road. CP indicated that they would not likely approve whistle cessation until an engineering solution to the trespass issue was implemented. We assume that such a solution would also have to address the issue of wildlife trespass onto the tracks, although this was not mentioned in the town’s documents.

The town council decided December 13th, 2021 to delay engaging an engineering firm to conduct the audit at Norquay Road until an engineered solution to the pedestrian trespassing issue has been approved. This may end up being similar to the situation in Canmore.

Silencing the train whistles in town makes for a more pleasant experience, but may be counter-productive if measures are not also taken to keep wildlife (and humans) off the tracks. At present, that measure continues to be the sounding of the horns.

Resources

https://banff.ca/AgendaCenter/ViewFile/Agenda/_12132021-1094

https://banff.ca/AgendaCenter/ViewFile/Agenda/_01102022-1099

Richard Patching is President Emeritus of Patching Associates Acoustical Engineering Ltd.

Thursday, January 20, 2022

Noise Conference Rescheduled

 Spring Noise Mini-Conference Re-scheduled to October 2022


Once again, COVID-19 restrictions have led the AANViS board has decided to postpone the 1-day mini-conference from April 22, 2022 to October 28, 2022. The location has not changed and we are in the process of contacting all of our speakers and panellists to make sure they are still available.

If you are unfamiliar with the plan for the day (or have just forgotten it over time), visit our conference page on this website. We look forward to seeing you this Fall.

Monday, October 4, 2021

Stopping Train Whistles through the Banff Townsite

Richard Patching, PEng, MEng

Some residents of Banff have petitioned the town council to restrict or eliminate the sounding of train whistles in the vicinity of the town. This was reported by the Rocky Mountain Outlook on March 29 and on Global News on April 8 of this year, after the presentation of a request from a delegation on March 22.

During the May 10 meeting of the Town Council, related correspondence, including written and verbal submissions, was received and the council passed a motion to have the Town’s Administration consult “with the railroad operator on the feasibility of creating a railway quiet zone along the railway corridor in the vicinity of Banff, and report back to Council before the end of Q3 2021.”

The Rocky Mountain Outlook article noted that one of the most impacted properties is the Mount Edith House seniors’ residence, which backs onto the train tracks (shown here). The report states that there are no noise-attenuation walls at this location. A visit to the site indicates that the band of evergreen trees between that building and the tracks is insufficient to address community concerns.

In the 1970s and 80s, the Canada Mortgage and Housing Corporation (CMHC) produced a document entitled CMHC - Road and Rail Noise Effects on Housing, which specified ‘acceptable’ levels of noise from trains, in particular between the ‘whistle points’ which are 400 metres from any uncontrolled level crossing. Under the Railway Safety Act (R.S.C., 1985), trains are normally required to sound their horns within the whistle points until they were actually occupying the level crossing, or when it is required for safety reasons such as trespassing people or animals. The Act [section 23.1 (1)] allows municipalities to pass a resolution to discontinue use of train whistles under the conditions now set in motion by the residents’ petition. There are only limited measures to prevent animals (who cannot read the signs) from accessing the tracks.

The Global News video shows the level crossing with crossing bars, so it is ‘controlled,’ but there are free-running animals in the Banff area, and access to the tracks within Banff is not consistently blocked by fencing. It has been noted that spillage of grain has attracted animals to the tracks in the past, potentially bringing wildlife onto the tracks and requiring the sounding of the trains’ horns to drive them away.

Previously, the nearby Town of Canmore required developments outside a corridor adjacent to the CP tracks to comply with the CMHC directives. This effectively sterilized the narrow corridor from residential developments within the mountain valley location. Fencing on both sides of the tracks has been installed to control access and some years back, the Town of Canmore was able to drop this non-residential building requirement from their planning regulations. This may have coincided with their establishment of a rail quiet zone, as is being requested in Banff.

The original existence of the Towns of Canmore and Banff is due to the presence of the railroad. The mine under the Three Sisters Mountain, and the mine at Anthracite (currently under Lake Minnewanka) supplied coal for the locomotives, and Banff was intended to support tourists attracted by the local hot springs, scenery, and wildlife. Silencing the train whistles in town makes for a more pleasant experience, but may be counter-productive if measures are not also taken to keep wildlife off the tracks which would still require the sounding of the horns.

As of the October 4, 2021 Banff Town Council meeting, there does not appear to have been any further information from the Town’s administration nor from CP Rail (https://banff.ca/AgendaCenter

Richard Patching is President Emeritus of Patching Associates Acoustical Engineering Ltd.

Friday, September 24, 2021

Noise Monitoring for Renewable Energy

Henk de Haan, dBA Noise Consultants

Many a tome has been penned about sound level monitoring, and many more could be added. Some of my incomplete thoughts on it are offered here.

Under most regulatory regimes, strategies for noise and sound monitoring are determined by the situation and the dominant noise sources at hand, and not by whether the source is renewable or non-renewable. Continuous sources are typically easier to monitor than sources with a highly variable noise emission, such as wind turbines.

Prior to constructing and operating any new development, getting an idea of what the current soundscape entails helps to put future noise levels into perspective and is therefore recommended. I use the word “sound” to indicate that the acoustic signals we hear are not all experienced as noise. Noise is unwanted sound, and the soundscape may include both appreciated sounds (e.g., songbirds, leaf rustle) and unwanted sounds (e.g., an existing non-renewable energy facility or other sources not covered by most noise regulations, such as highways or gravel operations). In that respect, ambient sound level monitoring is not any different for renewable energy compared to other facilities.

The monitoring of ambient sound levels is not required nor encouraged according to regulations in Alberta or British Columbia, but frequently requested by residents close to new developments such as a new wind farm. Apart from satisfying popular demand, the only time you get to measure the unaffected soundscape is before construction starts. Therefore, I believe that ambient sound level monitoring should be actively considered before any development, renewable or otherwise, unless the new development will not generate substantial noise. The cost associated with noise monitoring is minimal compared to the investment in the renewable’s facility itself.

Monitoring of sound levels during construction can help one gain insight into and limit noise levels associated with construction, provided noise limits are enforced; what gets measured for enforcement purposes gets done, while what gets measured for general insight often only gets discussed. Sources such as tonal backup alarms, loud radios, pumps, light tower generators running during the daytime may cause unnecessary grief, while solutions such as broad-band backup alarms are readily available.

Monitoring during operation can provide insight into noise levels, associated with the new facility. Monitoring, however, needs to be part of enforcement of applied noise thresholds. I, therefore, believe that the regulator should conduct noise monitoring as part of their enforcement as well, and not only oblige operators to conduct noise monitoring. Regulatory noise monitoring will increase public confidence. Noise from wind farms is dependent on weather and meteorological conditions, such as atmospheric stability, and with larger turbines this dependency may increase. Predictions made using a relatively simple standard like ISO 9613 are valid for a single weather and operations scenario, and receptor-level noise levels can be expected to deviate frequently from the predicted value. Longer term noise- and weather-monitoring for receptor-level noise levels and their weather dependency can be helpful to increase insight into their dependency and confirm predictions. It can also be helpful to develop a science-based and accepted protocol for such monitoring.

For more continuous sources (e.g., solar power, biomass), where sound noise generation is relatively steady, such extended monitoring is probably not required. Noise from inverters has a continuous character, and dependency is restricted to insolation (i.e., the varying level of electrical generation due to the incident solar intensity). Short-term measurements may, therefore, be sufficient.

Alternatives to noise monitoring could include model calculations, based on verified emissions combined with model calibration. Such an alternative could be useful in situations where receptor-level noise monitoring includes significant difficulties or where compliance can only be predicted with a significant margin.

Henk de Haan is President and Sr. Consultant at dBA Noise Consultants

Friday, June 18, 2021

Semi-Permanent Noise Monitoring

Jonathan Chui and Azar Sagiyev, Stantec Consulting Ltd.
 

Semi-permanent noise monitoring equipment with remote access has been available for at least a decade, but the technology has evolved with advances in internet speed and wireless connectivity.  Early on, we spent considerable time setting up an account with the wireless service provider and many hours struggling with the cell modem IP configuration.  This has improved recently.
While permanent noise monitoring systems are common for airport authorities and marine port authorities in large Canadian cities, semi-permanent systems have been effective for noise monitoring in short-term construction and operation industrial activities. Most semi-permanent noise monitoring systems consist of the following main components:
  • Sound level meter, pre-amp and microphone
  • Weather station
  • Power source (i.e., AC and/or DC power)
  • Cell modem
  • Data storage
Semi-permanent systems have many advantages, which include
  • Providing continuous noise monitoring for intermittent events with unplanned schedules (e.g., construction activities)
  • Reducing multiple visits to the monitoring site, especially for remote locations
  • Giving easy access to real-time noise monitoring results for users (e.g., clients, consultants, other stakeholders) via the internet
  • Providing a noise threshold exceedance alert (i.e., SNS message) for immediate corrective action
  • Providing sufficient data-sampling
  • Automating the reporting process
Challenges associated with semi-permanent systems include
  • Data transmission is limited by cell coverage (satellite data providers are available but at significantly higher cost)
  • Connectivity can be intermittent in remote locations
  • Remote (e.g., cloud) data storage of audio recording is limited by connectivity
  • Continuous power sources may be required in some systems
  • Post-processing and data management can be labour-intensive due to the large amount of collected data
Semi-permanent systems come at higher cost; however, they provide versatility and functions not available with portable systems. The use of semi-permanent systems may be justified for long-term (e.g., multiple months) monitoring programs where intermittent and unplanned site activities may occur. Semi-permanent-to-permanent systems are also an indispensable tool for major infrastructure projects that require long-term data trends, such as large airports, marine ports and highways that undergo major operational changes or are expected to receive steady increase in traffic in long-term.

Are Electric Cars Quieter than Gas-Powered Cars on the Road?

The number of electric vehicles (EV) is increasing in Alberta and across the globe. While this will positively impact greenhouse gas emissions in our cities, the impact EVs may have on road noise is less well known. EVs are undeniably quieter than their internal combustion engine (ICE) counterparts at start-up and while “idling.” However, road-pavement noise becomes dominant at highway speeds, making EVs and ICEs similar. 

Patching Associates Acoustical Engineering (PAAE) measured pass-by noise levels of locally available compact SUVs, comparing EV and ICE models on a local Alberta highway at various speeds. The results are shown below and indicate that at the tested speeds of 20+ km/h, pass-by noise emissions of EVs and ICEs on typical local pavement did not differ significantly.

While electric vehicles have the potential to reduce noise with very slow speeds (under 20 kph) and during idling and acceleration from standstill—where engine-generated noise dominates, such as in very congested city centres—these data show that the rise of EVs is not going to drastically change the situation for Alberta residents who are currently most affected by roadway noise—those living near busy arterial and highway road infrastructure.

Thursday, June 17, 2021

Paradise Lost: The Wilderness is Not What it Used to Be

Henk de Haan & Virgini Senden

Freshly vaccinated, we decided it was time for a change of scenery, so we packed our recently-acquired second-hand travel trailer and hit the road. The trailer, like any other trailer, is packed with amenities to turn it into our home away from home—heating, cooling, cooking facilities (an oven and a microwave), a fridge with freezer, and a bed with a real memory foam mattress and a bedside reading light. After a lifetime of camping in small, portable tents and sleeping on wafer-thin camping mattresses not worthy of the name—the epitome of luxury.  All these amenities require electric power, of course, either supplied via batteries or via a hookup at the camping spot.

Our first camp site was not equipped with power at all. To prevent draining his batteries, a neighbouring camper schlepped a transportable generator in and ran the generator for about an hour each day around lunch time. The first time, I was sitting outside reading, enjoying the beautiful weather, the songbirds, the busybody squirrel—it was heaven! The generator in question was not equipped with any noise-mitigating features, and it showed. The birds, the squirrels, the rustling leaves—all gone. I sighed, went inside and closed the door.

When camping, you’re more exposed to the weather, and it can turn nasty. We had a spot of rain overnight, and when I woke up early the next morning, everything inside felt a bit damp. I sneaked out of bed and decided to try out the heating system to get rid of the dampness, thus making getting up a more pleasurable experience for my significant other (she’s sensitive that way). The furnace came on, and so did the fan. It turns out the fan is a small, high-performance fan, tearing the peaceful slumber of my beloved to pieces. I tried to restore peace by offering breakfast in bed, which was (thankfully) gracefully accepted. A golden rule for both camping and staying in hotels: bring earplugs!

Our next campsite, located in a popular National Park, had it all—or almost everything in the eyes of management. Opposite from our campsite, a construction crew was working to erect a new building quite close to an existing, also fairly new, one. The crew put in admirable hours, even on Saturday and Sunday—twelve-hour shifts at least. For their power, they relied on a generator, not on the outlets of the building less than 25 metres away. When we pointed out the option of plugging in their equipment to the camp operator, the young man stared at me and said that generators were allowed between 7 AM and 11 PM, completely missing the point.

The weather on this camping trip was warm. Neighbours a few sites over invested in an RV the size of a city bus, equipped with at least three AC units. Obviously, they liked it cool, including overnight. We reached for the ear plugs once more. Did I mention the grass mowers? Management likes the grass on the campsite short.

All in all, we had a lovely outing, but not a quiet one. Thankfully, we were not confronted with rowdy neighbours playing their favourite music over the outdoor sound system that any decent trailer comes with. I’m sure, however, we will in the not-too-distant future. I want to go home.

Wednesday, June 16, 2021

When Condos “Sing”: Assessing Wind-Induced Balcony Railing Noise


Condo balcony railings can generate noise in high-speed winds
 
Modern condo towers can be prone to unwelcome noise outcomes. Mysterious ringing sounds that rattled residents in central Edmonton, Alberta were suspected to be caused by strong winds acting on balcony railings from a new residential hi-rise. Condo towers can be wrapped in balcony railing panels of countless styles, shapes, and materials. At the height of the top floors of tall towers, wind shear produces wind at several times the speed at ground height, and the wind speed can be extreme.
Some perforated aluminum balcony railing designs can generate wind-induced noise
Some perforated aluminum balcony railing designs can generate wind-induced noise

In general, there are two types of balcony railing panel designs: a solid material (usually glass) or a perforated material (usually aluminum). While it may be possible for a solid glass railing to generate noise, it is not typically a concern we are called on to assess and/or mitigate. On the other hand, when it comes to perforated aluminum railing designs on condo balconies, there are many possible combinations of wind speeds and angles of attack that can induce unwelcome sound.

The Benefits of Acoustically Assessing Balcony Railing Design Early on in a Project

Given the complexity of the mechanism that produces tonal sound from balcony panels, and given the cost of retrofitting existing panels, it is important to consider how a balcony railing panel will behave in the wind before the panels are installed, during the design phase.

Aeolian excitation (a.k.a. the wind) can cause a structure to vibrate, which under certain conditions and within a certain range of frequencies can lead to unwelcome sound. Thin, flat surfaces, like balcony railing panels are particularly good at converting vibration to sound, much like the diaphragm of a speaker.

There are two dominant mechanisms that can produce wind-generated noise at the perforations: vortex shedding, where the wind passes along the face of the railing over a repeating pattern of holes or slots, and jet noise due to wind flowing through the perforations. A third mechanism relates to the Helmholtz resonator effect, similar to blowing over the top of a bottle, but the lack of a defined volume behind the balcony panels renders this mechanism inapplicable.

The likelihood for a balcony railing panel to generate noise is dependent on many factors, including but not limited to the wind speed, the angle of attack of the wind, and the size and shape of the perforations. Because the flow of the wind over a small area is extremely difficult to predict or to model accurately, the interaction between the balcony railing panels and the wind is also difficult to predict. Therefore, we have found the most comprehensive way to evaluate how a balcony railing panel will behave is to test it in a wind tunnel.

Wind tunnel testing balcony railing design for possible wind-induced noise generation
Wind tunnel testing balcony railing design for possible wind-induced noise generation

Wind-Tunnel Testing of Balcony Railing Design Mock-ups for Noise

HGC Engineering has been called on by several developers during the design phase of a project to test full-sized balcony railing mock-ups inside of a wind tunnel. The wind tunnel environment allows us to measure the behaviour of a balcony panel design at any wind speed and angle of attack in a controlled and predictable environment, and to evaluate several perforation designs for their potential ability to generate sound under varying wind conditions. Wind speeds of up to hurricane strength can be tested with the proper setup.

Acoustical results of wind tunnel testing on balcony railing panel design
Acoustical results of wind tunnel testing on balcony railing panel design

During wind tunnel testing our acoustical consultants measure sound, vibration, and wind speed data in high-resolution in a variety of locations on and near the mock-up, using state-of-the-art acoustical instrumentation. The complex interactions between the balcony railing panel and the wind is analyzed to ensure that no wind-induced tonal noise is present. Should tonal noise be detected, we can then assess the cause and recommend various options to the project development team, including changes to the panel design or retrofit options for an existing panel. In many cases, these options can be tested and verified within hours.

Excerpted with permission of HGC Engineering.

To read the entire original article: https://acoustical-consultants.com/built-environment/balcony-railing-designs-and-wind-induced-noise/ 

Monday, May 11, 2020

Mini-Conference in the Works


A 1-day mini-conference will be held April 22, 2022 at the Coast Plaza Hotel and Conference Centre in Calgary. We are pleased to announce that the lunch-time keynote speaker is Jeremy Bridge of PK Sound, who will share his work on designing speaker systems for outdoor concerts that significantly reduce noise complaints from those living near the concert site. Half-day workshops will offer an Introduction to Acoustics and a review of Alberta Noise Regulations. Alternate sessions will address why noise consultants cost so much, designing an effective RFP, stories of what didn't work and why (and what was done to fix the problem), how to become a good consultant, and new tech and old pros. Click here for more details.

Recommended Podcast

Dr. Marcia Jenneth Epstein of the University of Calgary has a new podcast out for those who are interested in a sneak preview of the material in her new book, "Sound and Noise: A Listener's Guide to Everyday Life." The podcast is at

https://www.somethingyoushouldknow.net/492-why-the-world-is-doing-better-than-you-think-what-your-musical-taste-says-about-you-2/