Measuring (HIT & REM)

Basic measurement operations:

Figure 21a: Editing mode

The following steps are necessary to perform a measurement (Figure 21a):

Click on <HIT>, to perform measurements in the test box.

Or click on <REM>, to perform real ear measurements.

Select one of the available procedures you want to perform:

<f>: Frequency measurements

<single>: Single value measurements

<i/o>: Input-output measurements

<perc.>: Percentile analysis

<3-D>: 3-D measurements

<at-rt>: Attack and release time measurements*

<l-t>: Long term measurements*

<...>: Series of measurements*

<delay>: Processing time measurements*

<cr>: Dynamic compression ratio measurements*

<snd>: Analyzing procedures can be applied to a measurement performed over a selected time period*

<ri>: Right side is selected

*Measurements that can only be performed in the test box.

Click <go> to start the measurement. Enter on the keyboard can also be used to start the measurement.

Clicking <go> means that a measurement is enabled, starting, or still running. In this mode, all other buttons in the selection bar are gray and cannot be selected. This locks all other selections during a measurement.

Figure 21b: Measurement mode

To cancel a measurement or to return to the edit mode, press the <go> again (Figure 21b).

The Enter key on your keyboard may also be pressed to start a measurement and the ESC key may be pressed to cancel a measurement.

A drop down menu can be displayed from the right edge of some buttons (Figure 22). This selection menu provides a preset number of measuring methods with different settings.

A check mark will be displayed to show the measurement that is selected. Figure 22 shows a pure tone measurement at an input level of 60 dB. Gray highlighted menu items (here the REUG measurement) are menu items which are not available.

Figure 22: Button selection menu

When you move the mouse cursor over a button, information about the current measurement will appear (Figure 23).

Figure 23: Information text

The drop down menu for the <go> button provides measurement options (Figure 24).

Figure 24: Selection menu

one-time:

A single measurement is performed.

continuous without averaging:

Consecutive measurements are performed without averaging, until <go> of ESC is pressed again to cancel the measurement

The last measurement is always displayed.

continuous averaging:

Consecutive measurements are performed without averaging, until <go> of ESC is pressed again to cancel the measurement

A mean value is taken over all measurements.

average measurements 2,5,10,15,30,50,100:

The selected number of average measurements is performed.

Results may vary depending on the settings in the selection menu discussed above. For more information please refer to the section: "Working with ACAM."

The ACAM System can administrate a maximum 25 curves of each type of measurement per page.

If this maximum is reached, any further curves cannot be recorded (Figure 25).

Figure 25: Maximum reached

Pure Tone Measurements:

The pure tone measurement is performed in a cycle according to the RMS procedure.

The ACAM System can also perform Fast Fourier Transform (FFT), which provides more exact data. FFT provides additional data to the measurement frequency (all harmonics).

Reduce the number of the measured frequencies to obtain a more frequency-specific response and reduce the calculation time. Please refer to the section for information on how to change these settings: "Test box real ear setup."

Measurement Frequency Resolution

Resolution	Frequency Measurement Number of measuring points (Default setting)	Input/Output Measurement Number of measuring points (Default setting)
Very Good	221 frequencies from 100 Hz to 10000 Hz	120 levels from 40 dB to 100 dB
Good	110 frequencies from 100 Hz to 10000Hz	60 levels from 40 dB to 100 dB
Medium	64 frequencies from 200Hz to 8000 Hz	30 levels from 40 dB to 100 dB
Fast	38 frequencies from 200 Hz to 8000 Hz	10 levels from 40 dB to 90 dB
Very Fast	19 frequencies from 200 Hz to 8000Hz	4 levels from 50 dB to 90 dB