Meyer Sound SIM 3 User's Guide download pdf (Page 10)

CHAPTER 1

SIM 3 Measurement Terminology

MEASUREMENT: A method of capturing, calculating, transforming, and displaying a sample

of data, resulting in a useful/interpretable presentation of that data. Examples of SIM 3 mea-

surements are Band Spectrum, Line Spectrum, Delay Finder, and Frequency Response.

VIEW: A way of looking at a captured sample of data (or an ongoing sample of data) that

does not change what data is captured and recorded or how it is captured and recorded.

Examples for SIM 3 are Smoothing and Trace Offset. Console, Processor, Room, and Result

are also views, in which a particular portion of the measured data is formatted and graphed.

SETTING: A setting changes what data is measured, or how the data is measured, by vary-

ing the quantity, quality, or type of data that is sampled; examples in SIM 3 include adjust-

ments of Amplitude threshold, number of Averages, and Coherence threshold.

MODE: A temporary rearrangement of the Live Branch and its component sources so that

different aspects of a total system may be isolated and measured; examples in SIM 3 include

Lobe Study, Console Check, and Mic Compare.

PROCEDURE: A procedure is a particular specialized measurement task, including all of the

steps necessary to accomplish it. In SIM 3, the procedures are detailed step-by-step, and

following them will result in a successful measurement. Examples include Set System Delay,

Verify Coverage, and Mic SPL Calibration.

TRANSFER FUNCTION: A transfer function is the relationship or difference between the

input and the output of a system. It is the mathematical calculation of how an original signal

(audio, light, vibration, etc.) differs from a resulting signal as the energy passes from one form

to another or through some transmission medium. The measurement integrates elements of

time, phase, and frequency.

FAST FOURIER TRANSFORM (FFT): The Fourier transform converts the time domain repre-

sentation of a signal to the frequency domain (spectrum) or vice versa. An FFT is an opti-

mized implementation of this transform that can more efﬁciently calculate transfer functions

involving large sample sizes, and with computer processing can deliver real-time results. It

breaks the original transform’s complicated calculations into a series of simpler, easily solv-

able elements that can be recombined to produce the same results.

BAND SPECTRUM: The Band Spectrum measurement shows the level of energy that is

present in the tested signal for each 1/3-octave band across the entire measured spectrum.

The band spectrum integrates the energy over a particular group of frequencies, and pres-

ents it as one value — as a single horizontal line representing the total energy in that band.

Figure 1.1. Band Spectrum measurement, showing spectrum (white), spectrum max (yellow) and spectrum max

hold (red)

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Meyer Sound SIM 3 User's Guide Page 10