Sound and Noise
Decibel scale: sound levels typically created by souces of noise in the home and community
As Vancouver's population grows, so does the noise in our city. This website aims to inform you about what sound is, what the City is doing about it, and how to better control, reduce, or avoid it.
What is sound?
Our ears are sensitive to tiny fluctuations in air pressure that are created by vibrating objects. The fluctuations and the sensations they produce in our ears are called sound.
Sound travels in waves, spreading out from its source like ripples on a pond. The stronger the motion of the source, the louder the sound. The faster the source vibrates, the higher the frequency or pitch.
How is sound measured?
Sound is measured on a decibel scale and expressed in dBA. This logarithmic scale is similar to a Richter Scale which is used to measure the magnitude of an earthquake. The range for normal hearing is generally between 0 and 130 decibels (dBA).
"Sound level meters" are the instruments used to measure sound. They consist of a microphone in combination with an electronic amplifier and filter, a display meter and commonly today, a digital memory for data logging.
A historical look at urban noise
Noise has been a concern for city dwellers since Roman times when rulers passed a bill that prohibited chariot driving through the cobblestone streets of Rome at night. Noise levels have increased steadily with the growth of mechanization. By 1899, excessive noise was the number one "quality of life" complaint in New York City. Today, electronic sources such as powerful stereos, video games, car alarms, background music in stores and cell phones have added to the urban din.
Noise levels in our-day to day lives
In our daily lives we are rarely exposed to sound levels near either end of our huge (0 to 130 dBA) audible range. Typically we encounter noise levels between about 20 and 30 dBA (a faint whisper or night-time background noise in a quiet suburban bedroom) and 100 dBA (unmuffled motorcycle or jackhammer operating nearby). Typical noise levels experienced include:
- 40 to 50 dBA in a general office situation.
- 60 dBA when talking normally to someone 1 to 2 m away.
- 65 to 75 dBA when riding in a car at highway speeds.
- 85 to 95 dBA while cutting the grass with power mower.
Roughly speaking, each 10 dBA increase in sound level corresponds to a "doubling of subjective loudness" so that, for example, jackhammer noise at 110 dBA would typically be judged to be 2 x 2 x 2 x 2 = 16 times as loud as the inside of a car at 70 dBA.
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