Quiet! Please?

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This morning many of my fellow audio journalists and enthusiast audio manufacturers are either on their way or already arrived at the annual Munich audio show. Thinking about Munich focused my thoughts on one of the main reasons that many systems sound mediocre or just plain bad at audio shows - ambient background noise levels.

Several years back I started measuring the sound pressure levels at audio shows, including CES and the Rocky Mountain Audio Fest. I found that "quiet" rooms at shows ranged from an average background level of 45dB to 50 dB. Rooms with what I'd consider "loud" background levels started at 50 dB and went to a high of 60 dB. That means that a system in a loud room must be playing at 15 dB louder levels to achieve the same contrast between loud and soft as the quiet rooms. On many systems that 15 dB is the difference between working well with its comfort zone and pushing into distortion.

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But how does the background levels at shows compare to a home listening environment? The difference can be as great as listening in a quiet wooded glade verses Grand Central Station. Let's take my own listening rooms as an example. My noisiest listening room, which is right next to the kitchen and shares walls with my living room and has several working fish tanks, has an average ambient background level of 42 dB. This is nearly the same level as the average background levels outside my home.  At 3:45 PM on a Tuesday afternoon, my dB meter registered 40 dB outdoors.

My main listening room is the quietest room in my house. The average background levels are 32 dB. When you compare this to a "quiet" audio show hotel room at 45 dB, you can see why a system can sound better at home than at a show. Even my computer audio system in my office, at 36 dB ambient noise level, is 9 dB better than a "quiet' audio show demo room. Compare my quietest room with the highest levels I've recorded at a show and You'll find just under a 30 dB difference in background noise levels. That is huge.

The next time you go to a hifi show or a enthusiast audio store, check the background noise levels, and then go home and take some measurements in your own listening room. You may be surprised to discover how much difference you'll find.

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