Acoustics; Test For Prominent Discrete Tones (Pdts) - Seagate ST250DM000 Product Manual

2.10

Acoustics

Drive acoustics are measured as overall A-weighted acoustic sound power levels (no pure tones). All mea-
surements 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.
Note. 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)
Table 13: Fluid Dynamic Bearing (FDB) motor acoustics
ST3750640AS, ST3750840AS, ST3500630AS, ST3500830AS
ST3400620AS, ST3400820AS
ST3320620AS, ST3320820AS, ST3300620AS, ST3300820AS,
ST3250620AS, ST3250820AS, ST3200820AS
ST3250410AS, ST3250310AS
ST3160815AS, ST3160310AS, ST3160215AS, ST3120815AS,
ST3120215AS, ST380815AS, ST380215AS, ST340815AS,
ST340215AS
*During periods of drive idle, some offline activity may occur according to the S.M.A.R.T. specification, which may increase acoustic and
power to operational levels.
**Measured in performance mode.
***Measured in quiet mode.
2.10.1

Test for Prominent Discrete Tones (PDTs)

Seagate follows the ECMA-74 standards for measurement and identification of PDTs. An exception to this
process is the use of the absolute threshold of hearing. Seagate uses the lower limit for the threshold curve* to
discern tone audibility and to compensate for the inaudible components of sound prior to computation of tone
ratios according to Annex D of the ECMA-74 standards.
* Defined as the median curve given by ISO 389-7 (Tf curve) minus 10dB at all frequencies.
Barracuda 7200.10 Serial ATA Product Manual, Rev. K
Idle*
2.8 bels (typ)
3.0 bels (max)
2.7 bels (typ)
2.9 bels (max)
2.5 bels (typ)
2.9 bels (max)
2.6 bels (typ)
2.7 bels (max)
2.8 bels (typ)
3.0 bels (max)
Seek
3.7 bels (typ)**
3.9 bels (max)**
3.4 bels (typ)**
3.6 bels (max)**
3.0 bels (typ)**
3.2 bels (max)**
2.7 bels (typ)***
2.8 bels (max)***
3.0 bels (typ)***
3.2 bels (max)***
35