Can We Quiet Down About Noise?

The sound we hear is measured in terms of the pressure of the sound waves on our ears and is expressed in decibels or dB. Sound ranges from about 40 dB, as in an office or library, 50 dB in a large office, 70 dB in freeway traffic, 85 dB in a noisy restaurant, 90 dB in shouted conversation, 110 dB in a symphony concert or near a baby crying, 150 dB near a jet engine at takeoff max power, or 180 dB by a rocket launching.

Noise concerns are not new. In a 1978 study of all noise sources, for the Federal Interagency Committee on Noise, Dr. T.J. Schultz ascertained that human beings exposed to all sorts of community noise had differing sensitivity levels. That is the key point in this seminal work. Schultz determined that 12.5 percent of the 300,000 people surveyed complained about noise irritation at 65 dB. That landmark work has been updated in a more confined aviation noise setting, and it has been determined that perhaps 20 percent to 40 percent of those surveyed complained of irritation at 65 dB, but acoustics scientists have opined that response to aviation noise may be influenced by factors other than just sound level itself.

However, the 65 dB noise level is between that of a large office and freeway traffic, and it is close to the level of normal interpersonal speech. The key here is Schultz’s recognition that human beings have varying sensibility to sound. Some folks are just much more sensitive than others. 

So how does our community feel about noise? Concerns about aviation noise date back to 1928 when a farmer living near the eastern edge of what is now Van Nuys Airport got an article in the local newspaper reflecting his complaint about the noise from jennies flying in and out of the airport, causing his chickens to lay fewer eggs. Action about aviation noise got serious in about 1985, when prior to adoption of the Airport Noise and Capacity Act in 1990, the Los Angeles Department of Airports persuaded the FAA to allow it grandfathering privileges to adopt a noise ordinance restricting aircraft operations on the basis of noise output. Mayor Tom Bradley attempted to prevent this action from moving forward but could not achieve rescission of the previously adopted ordinances that were the basis for grandfathering. 

By 1998, Van Nuys Airport noise was an issue at City Council carried by activists demanding adoption of a noise constraint action. To clarify the issue, an independent consultant, California Survey Research Services Inc., was engaged to do a community sensitivity survey reflecting many pressing issues. To gauge the degree of sensitivity to airport noise, the survey of 400 randomly selected households, distributed across six council districts in the Valley, examined 10 issues of serious community concern. Respondents were asked to grade each of the issues with scores of 1-5, with 5 being “Extremely Important,” 1 being “Not at all important” and 3 being the indifference level. It should be recalled that at the time Valley secession was a major topic on everyone’s minds and all of the issues were hot buttons across communities. But in the detailed scoring of the results, crime was the hottest issue at 4.7105, followed by emergency medical care, schools, fire protection, graffiti, traffic and street maintenance. They were followed by public transportation, over development and airport noise at the bottom at 2.5779, or 14 percent below the indifference level.  

The survey, in the context of Dr. Schultz’s work, is very compelling.  Work subsequent to Dr. Schultz’s argues that sensitivity to noise at 65dB is now held to be at higher percentages ranging from 20 percent to 40 percent, but the key issue of differing levels of noise sensitivity remains unchallenged.

 One common complaint about airport noise is that it causes diminution in home values. A 1994 study by Booz Allen and Hamilton affirms that home values in airport noise impact areas are indeed diminished by that noise. However, this argument is only valid in comparing the value of homes purchased in an area having not previously been impacted by aircraft noise, and at time of sale is subject to new airport noise. This is a crucial factor in assessing the degree of home value diminution due to airport noise.  

The first jet engined aircraft were present at Van Nuys in 1965, a time of very noisy jet engines, and much lower ambient noise levels in the community. Thus, the impacts of the jets would have been very noticeable since that date. Given this situation, assessing home value diminution on a home sold today, for there to be any basis for arguing loss due to airport noise, the homes must have been purchased before 1965 or 1970, for the jet noise impact factor to bear. Consider, if one buys a home subject to airport noise, the purchase price will be diminished and at the time of sale the price will also be diminished. In an analysis applying the observations of Booze Allen, the holding term yields on noise-free homes versus noise-impacted homes is virtually identical, thus there is no loss attributable to airport noise.

The above discussion is based in its entirety on facts that very brief research will confirm. If one can find valid data that will repudiate the observations, it will be readily accepted. But to simply make an observation of fallacy, will not advance the discussion. 

Robert Rodine is owner of the Polaris Group, a Sherman Oaks-based financial and economic consulting firm that specializes in transportation issues, particularly aviation. He has chaired or co-chaired the aviation committee of the Valley Industry and Commerce Association for 11 years.