GMW GMW14055 PDF

Note: Nothing in the specification supersedes applicable laws and regulations unless specific exemption has been obtained.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose. To provide a common procedure for recording the sounds of subsystems (that can be directly actuated by the customer - "Customer Actuated Sounds" - CAS) for analysis for sound quality evaluation using measuring mics.

Forward. The sounds of subsystems must be recorded to apply the objective methods for Sound Quality Metric evaluation. Many subsystems have multiple modes of operation. Each mode of operation must be recorded independently for evaluation and comparison. This procedure is intended to describe the operating conditions of the subsystems, the recording methods to be used, and the various analysis methods that may be applied to the recordings for the objective Sound Quality Metric evaluations. Not all the analysis methods described in this procedure need to be applied to the sounds of every subsystem. The requirements for the individual subsystems will identify which methods are to be used.

Applicability. Any subsystem or component that is installed on vehicles and can be directly actuated by the customer.

Definitions.

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

Relative Pitch: an objective method of scaling changes in tonal component time histories (or motor speed time histories) so that the changes can be compared to the musical equal tempered scale. The results of the method are relative (not absolute) just as in music the interval of an octave is a constant ratio between two tones and is valid anywhere in the range of musical notes.

Percentile Frequency: The xx-percentile frequency is the frequency below which the partial loudness of a given Specific Loudness Pattern contributes xx% to the total loudness determined by the pattern

Note: the total loudness is proportional to the total area of the pattern. In this procedure the 70%-ile frequency is used.

Percentile Frequency Curve: The time-varying curve generated by connecting the xx%-ile frequency values for successive Specific Loudness Patterns in a continuous time interval. In this procedure the 70%-ile frequency curve is used.

Summed Exceedance: a summation of the amount that a given percentile frequency curve of an impulse is greater than the reference profile of the frequency content requirement. The percentile frequency curve of an impulse is compared to the reference profile on a point-by-point basis and weighted by the time resolution of the analysis. In this procedure the 70%-ile frequency curve is used.