Earlier this month, we lauded Hitachi's Deskstar 7K1000 terabyte hard drive for its industry-leading capacity. We weren't as impressed with the drive's noise levels, though. Under a seek load, the 7K1000 tipped our digital sound level meter at over 57 decibels, putting it at the loud end of 7,200-RPM drives on the market.

The drive we used for testing was a standard retail model, and by default, those drives come with Hitachi's Automatic Acoustic Management (AAM) disabled. Some of you suggested we test with AAM enabled, and we have.

Acoustic management is handled through a bootable feature tool disc that allows users to select a seek mode setting between arbitrary values of 128 and 254 in 1 unit increments. Hitachi defines values between 128 and 191 as falling under a quiet seek mode, with values between 192 and 254 considered normal seek mode. Interestingly, the tool's "recommended" AAM level is its quietest seek mode, which sits at the opposite end of the spectrum from the default "normal" level.

Going for broke, we set our 7K1000 to its recommended AAM setting and fired up our trusty sound level meter.

With AAM enabled, the 7K1000's noise levels drop to just 53.5 decibels under a seek load—nearly four decibels quieter than the drive's default configuration. A four-decibel difference is easy to hear with the naked ear, so why doesn't Hitachi enable acoustic management by default? In a word, performance.

Even Hitachi's AAM adjustment tool warns that setting quieter seek modes will decrease performance. But by how much? Quite a lot, at least in HD Tach's random access time test. AAM costs more than five milliseconds here, and while that might not sound like much, the resultant seek times are 40% slower than the Deskstar's default config.

Fortunately, AAM doesn't degrade performance across the board. HD Tach's read and write speed tests are unaffected, for example, and transfer rates in FC-Test are only marginally slower with acoustic management enabled. WorldBench is no slower with AAM enabled, either, and the performance hit in our iPEAK multitasking tests is negligible.

Seek performance matters more in some applications than in others, though, as evidenced by our IOMeter test results.

Transaction rates are generally slower with AAM enabled, although the severity and consistency of the performance hit varies depending on the test pattern.

In the end, then, Hitachi's Automatic Acoustic Managment does in fact lower the 7K1000's seek noise levels to more reasonable—even impressive—territory. However, keep in mind that relative silence does penalize seek performance.