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The Science of Sound
Whether our not you're a specifying engineer, you probably know how important it is to meet all the needs of the end user when it comes to providing the right equipment for the project. You also know sound requirements are becoming more important for most users to ensure they remain good neighbors. In this article I hope to give you some "sound guidance" on a few of the common misconceptions of dealing with sound.
 | | Decibel Meter |
Understanding sound is not exactly rocket science, but thoroughly comprehending this "exact"/inexact science takes some study. What complicates things is that there are at least three different qualities of sound that can be measured. Those qualities include Loudness (or Volume), Power (or Intensity) and Sound Pressure. What makes this confusing is the fact that, when there is a doubling of Power, it results in a 3dB increase. When sound pressure is doubled, it results in a 6dB increase, and when loudness (which is what is perceived by the human ear) is doubled, it results in a 10dB increase.
The measurement we use to measure sound is the decibel (dB). A decibel is 1/10th of a Bel (named after Alexander Graham Bell). Any respective sound is actually multiple frequencies of sound combined. Although lower frequencies create higher sound pressure levels, they sometimes don't sound as loud as higher frequencies. The audible range of sound capable of being heard by the human ear is between 20Hz - 20,000Hz. This brings us to the subject of utilizing filters to measure sound.
Sound pressure is not measured with any type of filter, but when measuring loudness, it becomes beneficial to filter some of the frequencies to better simulate what the human ear perceives. Some of the most common filters are "A", "B", "C" and "D". These filters are "weighted", meaning that they combine all frequencies being measured to get a single dB rating. As with any filter, each one eliminates various frequencies from the measured sound spectrum. The standard filter for sound measurement that takes into consideration the human ear's sensitivity to certain frequencies is the A-weighted filter shown as either dB(A) or dBA. The "A" filter eliminates specific high and low frequencies that are unable to be heard by the human ear, which makes the dB(A) readings more applicable in some instances. The "A" weighted filter is the one most often used in the industry when specifying a... (complete article here) |
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Question: What does the word isochronous mean and why is it important?
Answer: Isochronous is a word derived from the Greek iso (equal) and chronos (time). It literally means regularly, or at equal time intervals. In general, it refers to something that occurs at a regular interval, of the same duration; as opposed to synchronous which refers to more than one thing happening at the same time. The term is used in different technical contexts, but in power generation, the term often refers to the governor and frequency regulation.
An isochronous governor keeps the frequency/speed of the prime mover at 60Hz, regardless of load - that is, within the limitations of the generator.
You may want to consider coming to one of our training seminars or workshops where we discuss all types of governors, including isochronous applications and how each system relates directly to today's power generators. Take a look here for more information on our classes and dates. Do you have a question for GT? Submit your question here. We answer every question. With your permission we may publish your question along with our answer in the next issue. |
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About GEN-TECH
We service equipment, made by every major manufacturer in the engine driven generator business, at locations throughout the United States and around the world. We take great pride in being your single source of responsibility for your emergency systems before and after the sale. We are your full service, one stop, generator system supplier combining sales, service, parts, rental and training under one roof!
Arizona Generator Technology, Inc.
dba: GEN-TECH7901 N. 70th Ave. Glendale, Arizona 85303 800-625-8324
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