Product manual

20 Barracuda 7200.7 Serial ATA Product Manual, Rev. C
2.11 Acoustics
Drive acoustics are measured as overall A-weighted acoustic sound power
levels (no pure tones). All measurements are consistent with ISO document
7779. Sound power measurements are taken under essentially free-field
conditions over a reflecting plane. For all tests, the drive is oriented with the
cover facing upward.
For seek mode tests, the drive is placed in seek mode only. The number of
seeks per second is defined by the following equation:
(Number of seeks per second = 0.4 / (average latency + average access time)
Note. During periods of drive idle, some offline activity may occur accord-
ing to the S.M.A.R.T. specification, which may increase acoustic and
power to operational levels.
Table 4: Fluid Dynamic Bearing (FDB) motor acoustics
Acoustic mode
Models Idle* Quiet seek Performance seek
ST3160023AS
ST3160021AS
ST3120026AS
ST3120022AS
ST380011AS
<2.5 bels (typ)
2.7 bels (max)
2.8 bels (typ)
3.0 bels (max)
3.4 bels (typ)
3.7 bels (max)
ST340014AS <2.2 bels (typ)
2.4 bels (max)
2.5 bels (typ)
2.7 bels (max)
3.1 bels (typ)
3.5 bels (max)