Tonight I measured a Sound Pressure Level (SPL) of 66dB(A) @ 25 feet from the property line as only 2 children screamed and yelled on the trampoline.

The SPL meter I was using has a lower measurement level of 60dB(A), so just seeing the meter move is >= 60dB(A). Since the allowable noise limit is 50dB(A)* after 7:00pm in Jefferson County, this is a violation of Jefferson County Law. (and would be a violation during the daylight hours too). I will be gaining the use of a wider range SPL meter shortly, but from what I measured tonight, that hardly seems necessary. Sixteen dB(A) over the legal limit is quite significant.

* "Periodic, impulsive, or shrill noises" have an even lower limit after 7:00pm of 45dB(A).

I haven't measured it, but I suspect the SPL measurements at the street or in the Mercers back yard would be MUCH lower. The screaming funnels or reflects off the side of their two story house directly into my house and backyard.

A Sound Pressure Level meter is non-discriminatory. It measures sound levels regardless of the source. All sounds are measured, from a jet airplane, screaming children on a trampoline or a loud college student party. To a Sound Pressure Level meter, sound is sound. The Jefferson County Noise Abatement Regulations differentiates between construction, vehicular and non-vehicular noise. The noise coming from the playground falls into the non-vehicular category.



Jefferson County Noise Abatement Regulations

Noise Primer

  • Intermittent noise is even more disturbing to people than continuous noise.
       -- League for the Hard of Hearing

  • Unlike air pollution which can be closed out, noise penetrates the walls of people's homes and is seen as a violation of their safety.
       -- American Psychologist


Because the human ear does not hear sound energy linearly (on a one-to-one basis), humans do not perceive changes in sound level as equally loud. Research indicates the following general relationships between sound level and human perception:
  • A 3 dB increase is a doubling of acoustic energy and is the threshold of human perceptibility.

  • A 10 dB increase is a tenfold increase in acoustic energy but is perceived as a doubling in loudness to the average person. The average person will judge a 10 dB change in sound level to be twice or half as loud.


FACTORS INVOLVED IN THE HUMAN REACTION TO NOISE
Source: Aviation Noise Effects, USDOT-FAA, March 1985.

  • Feelings about the Necessity or Possibility of Prevention of the Noise: If people feel that their needs and concerns are being ignored, they are more likely to feel hostile towards the noise.

  • Activity at the Time an Individual Hears the Noise: A person's sleep, rest and relaxation have been found to be more easily disrupted by noise than by communication and entertainment activities.

  • Time of Day: Noise intrusions are typically considered more annoying in the early evening and at night than during the day.

  • Season: Noise is considered more disturbing during the summer than in winter, especially in climates where, during the summer, windows are likely to be open and recreational activities occur outside more frequently.

  • Predictability of the Noise: Research has revealed that individuals exposed to unpredictable noise have a lower noise tolerance than those exposed to predictable noise.

  • Control over the Noise Source: Someone who has no control over the noise source will be more annoyed than one who is able to exercise some control.

  • Length of Time an Individual is Exposed to a Noise: There is little evidence supporting the argument that annoyance resulting from noise will decrease with continued exposures, and, under some circumstances, annoyance increase with longer exposures.