TITLE
    Macintosh Computers and LaserWriters: Noise Levels
Article ID:
Created:
Modified: 		8556
9/12/91
4/17/00
TOPIC

    This article provides information about noise levels from Macintosh computers and Apple LaserWriter printers.

DISCUSSION

    Acoustic noise is usually perceived as being how 'loud' a machine appears to a listener. To compare the 'loudness' of products, the International Standards Authority (ISO) has produced a number of specifications (including ISO 7779 and ISO 9295) that define acoustic noise terminology and how it can be measured, and a specification (ISO 9296) defining how the measured values should be declared in a consistent way. ISO has not, however, laid down any acoustic noise limits that IT Equipment (ITE) should meet; this has been left to government and commercial authorities to set.

    The specifications describe two measures of acoustic noise, Sound Power and Sound Pressure. Sound Power is effectively the total 'loudness' of a device while Sound Pressure is the measure of noise at a point in space. For Sound Power and all Sound Pressure positions, there are two measurement modes; idle, where the ITE is turned on and operational but not doing useful work; and operational, where the ITE is doing useful work (e.g. disk access). Sound Power is not affected by a change in environment whereas Sound Pressure is affected, since extraneous acoustic noise will affect the measurement.

    Acoustic noise is measured by sound pressure meters (it measures all sound coming from the ITE and all other influences, whether audible or not), and is statistically adjusted, called 'A-weighting', to relate it to the audible hearing range. These values are expressed as decibels (dBA).
    Noise Levels, Macintosh Computers
    Sound Power
    Sound Pressure at 25 cm
    Model
    Operational
    Idle
    Operational
    Idle
    iBook
    42 dBA
    34 dBA
    37 dBA
    29 dBA
    iMac
    44 dBA
    43 dBA
    32 dBA
    31 dBA
    iMac (Slot loading)
    39 dBA
    35 dBA
    31 dBA
    27 dBA
    PowerBook G3 Series (Bronze keyboard)
    49 dBA
    36 dBA
    41 dBA
    23 dBA
    Power Mac G4
    51 dBA
    48 dBA
    44 dBA
    39 dBA
    Power Macintosh G3
    (Blue and White)
    45 dBA
    42 dBA
    30 dBA
    29 dBA
    Power Macintosh G3
    desktop enclosure
    44 dBA
    42 dBA
    36 dBA
    34 dBA
    Notes
    * All sound pressure values were measured 25 cm from the front of each computer.
    * The hard drive noise levels vary within the same model from the same company and may result in slightly different results than that reported above.
    LaserWriters
    Standby
    Printing
    LaserWriter, LaserWriter Plus
    < 45 dB
    < 50 dB
    LaserWriter II
    < 50 dB
    < 60 dB
    Personal LaserWriter
    < 40 dB
    < 54 dB
    Personal LaserWriter 300/320
    36 dB
    46 dB
    LaserWriter Select 300
    36 dB
    43 dB
    LaserWriter Select 360
    36 dB
    47 dB
    LaserWriter Pro 600/630
    34 dB
    49 dB
    LaserWriter 4/600
    36 dB
    46 dB
    LaserWriter 16/600
    34 dB
    52 dB
    LaserWriter Pro 810
    40 dB
    53 dB
    LaserWriter 12/640 PS
    31 dB
    50 dB
    Color LaserWriter 12/600 PS
    45 dB
    55 dB
    LaserWriter 8500
    ~35 dB
    ~50.5 dB



Document Information
Product Area: Printers
Category: LaserWriters
Sub Category: General Topics

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