Harbourfront Community Association

627 Queens Quay W, Toronto, ostalCode w:st="on">M5V 3G3ostalCode>

August 25, 2009

For: Toronto Harbourfront Community

cc.   laceName w:st="on">TorontolaceName> laceType w:st="on">PortlaceType> Authority, Community Air

cc.   Mayor Miller, Adam Vaughan, Pam McConnell

Subject: laceName w:st="on">FederallaceName> laceType w:st="on">PortlaceType> Authority, Airport Noise Study - DBA Decibel Problems

In November 2008, the Toronto Port Authority invited representatives from community associations along the waterfront to participate in a Noise Advisory Committee. A TPA Noise Management Study was distributed for review, and will be discussed at the next meeting of the Noise Advisory Group in September 2009, after public feedback.

Question: Does the Community establish the rules for measuring noise from the airport, under the Tripartite Agreement, or does the federal port authority set the standards for measuring and assessing airport noise in our community?

The port authority is using dBA readings in its noise measurements. The community prefers to use dBC readings as a more complete measure of noise.  

In the view of the community, there is a serious problem with the federal port authority airport noise study - Adjusted dBA decibels are only partial measures.

Background Information: DBA and DBC Decibel Readings

There are 2 types of decibel (db) readings, called dBA and dBC. DBC is a complete sound reading, while dBA is a partial sound reading. dBA’s are 15% lower because they don’t measure bass. dBA is an Adjusted Noise Reading, which is used for PR purposes.

This is a quote from the TPA Noise Study. “Background residential sound levels are approximately 45 dB. The highest sound level, caused by a sports car, is approximately 70 dB, while an aircraft generates a maximum sound level of about 68 dB.”  

It looks like this quote from the TPA Noise Study, compares dBA noise readings for airplanes with dBC readings for sport cars. dBA readings minimize the noise problem. With dBA’s, the meter reading looks lower while the noise level remains the same.

More importantly, it’s just not true to say the highest sound level produced by an airplane is 68 db. Whatever scale that is, it’s wrong. Community noise surveys measure airport noises higher than 80 and 90 dBC. This much of a discrepancy in noise measurements indicates to us that the Port Authority Noise Survey is lying with statistics.

Using dBA noise measures is one way of lying with statistics, by not telling the whole story about airport noise. Plus, it’s garbage in, garbage out, regarding noise measures for NEF Airport Noise Modeling. Noise modeling means nothing if numbers are wrong. dBA noise measure are simply not valid indicators of the impact of airport noise on a neighboring community. Airport noise modeling should be using dBC noise measures.

Standard Noise Comparisons

It’s helpful to use comparisons when presenting information about noise levels, but the port authority noise report uses comparisons which are debatable, with an obvious bias for partial airplane noise readings. When dBA and dBC measurements are both used in a report, dBA (Adjusted Decibels) and dBC (Complete Decibels) should be specified. 

44 dBA = 50 dBC - quiet street, people talking

52 dBA = 60 dBC - traffic, normal neighborhood noises

60 dBA = 70 dBC - airplane takeoff, loud television, folk music concert

70 dBA = 80 dBC - airplane taxiing, loud stereo, jazz concert, ferry foghorn,

80 dBA = 93 dBC - airplane maintenance engine run-up, rock concert, party boat

85 dBA = 100 dBC - painful noise, police sirens, fire alarms, thunder 

Decibel Doubling Factors in Noise Measurement

It’s important to note that noise increases faster than decibels. An increase of 10 decibels doubles the noise. An increase from 60 to 70 dB doubles the sound pressure again. From 70 to 80 dB is another doubling of noise in your ears. By the time we hear 90 decibels, like at a loud rock concert, the noise (ie. sound pressure in our ears) is nearly 40 times louder than a quiet room sound of 40 dB.

Excessive Helicopter Noise -  Noise Abatement Measures proposed in the TPA study are obvious solutions to fix specific problems, and should be implemented immediately, but the Port Authority noise report does not address the problem of helicopter noise.

The Tripartite Agreement states that helicopter noise HAS to be counted in calculating the actual Noise Exposure Forecast (NEF). Remember, noise is additive and cumulative.

Porter's investors sought reassurance in 2005 that noise limits at the laceType w:st="on">IslandlaceType> laceType w:st="on">AirportlaceType> permitted the volume of Porter traffic they were planning for. Porter investors were given a report prepared by Pryde Schropp and dated October 25, 2005, but this report did not account for helicopter noise.

To ensure that total airport noise does not exceed NEF contour limits, this means either the frequency of Porter flights will have to be reduced from the level its investors were counting on, or helicopters will have to find another location to fly out of.

Tripartite Agreement on Noise - If NEF exceeds specified limits, the tripartite agreement is breached and the City can start taking action to shut the airport down.

Long Term Options – Remove Toronto’s Port from the Canada Marine Act.