Seagate ST3400820AS ユーザーズマニュアル

Barracuda 7200.10 Serial ATA Product Manual, Rev. K

35

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)

*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.

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.

ST3750640AS, ST3750840AS, ST3500630AS, ST3500830AS

2.8 bels (typ)

 

3.0 bels (max)

3.7 bels (typ)**

 

3.9 bels (max)**

ST3400620AS, ST3400820AS

2.7 bels (typ)

 

2.9 bels (max)

3.4 bels (typ)**

 

3.6 bels (max)**

ST3320620AS, ST3320820AS, ST3300620AS, ST3300820AS,

 

ST3250620AS, ST3250820AS, ST3200820AS

2.5 bels (typ)

 

2.9 bels (max)

3.0 bels (typ)**

 

3.2 bels (max)**

ST3250410AS, ST3250310AS

2.6 bels (typ)

 

2.7 bels (max)

2.7 bels (typ)***

 

2.8 bels (max)***

ST3160815AS, ST3160310AS, ST3160215AS, ST3120815AS, 

ST3120215AS, ST380815AS, ST380215AS, ST340815AS, 

ST340215AS

2.8 bels (typ)

 

3.0 bels (max)

3.0 bels (typ)***

 

3.2 bels (max)***