Noise & Vibration · Acoustics · Sound Quality · Instruction
for Products · Laboratories · Buildings · Plants · Machinery
Product Sound Quality
Noise & Vibration · Acoustics · Sound Quality · Instruction for Products · Laboratories · Buildings · Plants · Machinery
Product Sound Quality
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Sound Quality simply refers to the study of sounds as they are perceived by people. Although our acoustical analyzers come packed with functions that approximate human hearing, they don't listen: they do not assign meaning to anything they hear. People listen. And what they hear matters to them increasingly. While listening, people often make critical decisions about such key product image concepts as power, value, quality, longevity and need of repair. These decisions can be accounted for during the design and engineering phases, before the product reaches the street. How important is this to customers? The answers can be surprising. In the May 2000 issue of PC Professional Magazine (Germany), a number of current desktop PC models were evaluated. Look at the weighting factors used to assign the score:
Some computers received mediocre ratings solely on the basis of weakness in the area of sound quality. For each product the goal of sound quality work is to listen properly, i.e., to listen (or measure) as the customer listens and evaluate as the customer evaluates, then design appropriately. Product-Related Work
A manufacturer discovered that, although its products met all regulatory requirements, sales were sometimes lost (especially in certain offshore markets) strictly on the basis of noise. Stateside, an increased rate of calls to technical support was noticed. A plan was created to allow the manufacturer to develop an in-house sound quality program at a fraction of the cost of sending its units out for test. The program described calibrated recordings, listening evaluations, acoustical analysis and statistics to identify sound attributes that customers find preferable, and development of a model that predicts customer reactions based on measurable quantities.
A number of recent projects have involved applications of fans and blowers. These devices are ubiquitous but commonly misunderstood, especially with regard to noise emission. Designers and engineers often do not realize that an error in fan selection can result in significantly increased sound levels (as much as 10-15 dBA) as well as the exacerbation of annoying tones. Addition of silencers as an afterthought often has a negative impact on performance. Thus it is important to control the noise of the fan at the source, that is, create a flow system design that is inherently quieter.
Required cooling flow and power Fan Wheel Type and ideal Diameter or Speed System Resistance and Point of Operation Additional Load of Silencers, if needed Turbulence and Inflow/Outflow characteristics
Discharging compressed air is the single most efficient way to make noise in large quantities. However, compressed air is a relatively inexpensive and very common source of energy in industry, and therefore constitutes one of the most common problem noise sources. In situations where the thrust is not needed solutions are typically simple and inexpensive. If the thrust must be maintained, the following issues must be considered: Is this really an appropriate application of Compressed Air? Pressure and volume flow requirements Discharge distribution and location Discharge timing Obstructions in flow "...Thanks for your time and great presentation. I
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