Full Description

Note: Nothing in the specification supersedes applicable laws andregulations unless specificexemption has been obtained.

Note: In the event of conflict between the English and domesticlanguage, the English languageshall take precedence.

Purpose. To provide a common procedure for recording the sounds ofsubsystems (that can be directlyactuated by the customer - "Customer Actuated Sounds" - CAS) foranalysis for sound qualityevaluation using measuring mics.

Forward. The sounds of subsystems must be recorded to apply theobjective methods for Sound QualityMetric evaluation. Many subsystems have multiple modes of operation.Each mode of operation must berecorded independently for evaluation and comparison. This procedureis intended to describe theoperating conditions of the subsystems, the recording methods to beused, and the various analysismethods that may be applied to the recordings for the objective SoundQuality Metric evaluations.Not all the analysis methods described in this procedure need to beapplied to the sounds of everysubsystem. The requirements for the individual subsystems willidentify which methods are to beused.

Applicability. Any subsystem or component that is installed onvehicles and can be directlyactuated by the customer.

Definitions.

Zwicker Loudness Method: a phrase used to indicate that the processused to calculate a loudnessvalue generally follows some version of the method invented by E.Zwicker.

Relative Pitch: an objective method of scaling changes in tonalcomponent time histories (or motorspeed time histories) so that the changes can be compared to themusical equal tempered scale. Theresults of the method are relative (not absolute) just as in music theinterval of an octave is aconstant ratio between two tones and is valid anywhere in the range ofmusical notes.

Percentile Frequency: The xx-percentile frequency is the frequencybelow which the partial loudnessof a given Specific Loudness Pattern contributes xx% to the totalloudness determined by thepattern

Note: the total loudness is proportional to the total area of thepattern. In this procedure the70%-ile frequency is used.

Percentile Frequency Curve: The time-varying curve generated byconnecting the xx%-ile frequencyvalues for successive Specific Loudness Patterns in a continuous timeinterval. In this procedurethe 70%-ile frequency curve is used.

Summed Exceedance: a summation of the amount that a given percentilefrequency curve of an impulseis greater than the reference profile of the frequency contentrequirement. The percentilefrequency curve of an impulse is compared to the reference profile ona point-by-point basis andweighted by the time resolution of the analysis. In this procedure the70%-ile frequency curve isused.