The Test Sound menu is used to set the parameters for the test sound.
The test sound is available on the speaker configuration tab and serves the purpose of quickly verifying the correct connection to a speaker selected in the speaker table. A generated sweep, or one of the predefined Async measurement signals (see “Generator”) can be used for the speaker test. The playback is limited to 2 seconds.

The following parameters can be set in sweep mode:

• Gain: Playback gain in dBFS, only integers can be specified, positive values will be correct to negative

The following parameters can be set in predefined mode:

• Gain: Playback gain in dBFS, only integers can be specified, positive values will be correct to negative
• Selected signal: Choice of predefined signals

The Measurement Module guides through each step to perform a measurement. Select and configure a Scene

• The “Scene” screen displays various measurement scene options like  a left-hand drive car with two seats or inside a room.
• Selecting a scene here impacts two things:
  • The number of available microphone positions. This depends on the chosen scene like a two-seater car will have fewer microphone positions than a five-seater).
  • Microphone position numbering: This is based on the driving position (left to right for left-hand drive, vice versa).

Once you double-click on the desired scene, the “Speaker Configuration” window will open.

Microphone setup tasks such as calibration, channel selection, and mic compensation file selection can be done using the Mic Setup view, either before or after the microphone configuration on the car.

On the Microphone Configuration view, you can arrange and configure the microphone.

The available microphone arrays are located to the left side on the Microphone Configuration view .

• Single Microphone
• 4 microphones
• 6 microphones
• 16 microphones
• 4 by 4 array (to measure at 16 different microphone positions using 4 microphones in 4 steps at one array position)

You can perform following actions on Microphone Configuration window:

Positioning Microphone Arrays

• You can freely drag and drop microphone array anywhere in the scene.
• Dragging an array far outside the scene will remove it.
• If the same mic array is already configured in the Mic Setup view, the name, channel assignment, calibration, and compensation will be used from the Mic Setup view. Any changes made to the respective mic array in the Mic Setup view will also be applied to the dragged mic array.

Seat Position Assignment

• The mic array can be assigned to any available seat positions based on the selected scene. For example, in a 4-seat scene, the available seat positions are “None” (no fixed seat position), “Row 1 Left”, “Row 1 Right”, “Row 2 Left”, and “Row 2 Right”. Depending on the selected seat position, the mic array is placed in the car. If “None” is selected, the mic array will be placed at the position dragged by the user.

Managing Microphone Arrays

• A list of all microphone arrays in the scene is displayed on the right.
• Use the up and down arrows to change the order of the arrays in the list.
• Mic Array name is only editable in Mic Setup view.
• Click the delete button to remove an array from the list.
  

Soundcard Input Assignment

• Assigning a Sound-In stream channel to each microphone is only allowed in the Mic Setup view.

Rotating Microphone Arrays for Sequential Measurements

• Select “Rotating” for microphone arrays in the list to design a measurement sequence quickly.
• These arrays will automatically snap to each seat, acting as a mobile unit that captures audio at multiple positions.
• The seats will be numbered consecutively, indicating the measurement order.

The number of seats needs to be a multiple of the number of microphones in the rotating array.

• You can keep additional microphones on the scene as fixed positions for more comprehensive data collection. The placement logic for the rotation is as follows:

• • One mic all seats in order: driver (seat 1), passenger (seat 2), rear behind driver (seat 3), rear behind passenger (seat 4).
  • Two mics, two seat car: mic 1 on seat 1, mic 2 on seat 2.
  • Two mics, four seat car: mic 1 on seat 1, then on seat 2, mic two on seat 3 then on seat 4.
  • Two mics, six seat car: as for 4 seats plus mic 1 on seat 5 (driver side), mic 2 on seat 6.
  • Three mics, two seat car: forbidden.
  • Three mics, four seat car: forbidden.
  • Three mic, six seat car: mic 1 covers first row, mic 2 2nd, mic 3 3rd. First all on the driver, then on the passenger side.

The Measurement Module is used to perform synchronous and asynchronous impulse response measurements and recordings.

If you want to work with the Measurement Module, you don’t need an active project. GTT will automatically create da ummy project, where you can perform all the operations. In case there is an active project available, the Measurement Module session will be associated with it.

A device is not necessary for the Measurement Module to function in the project. The Measurement Module enables direct sound card measurements without an intermediate device, whereas tests controlled by gain channels can be carried out via a device.

Related Topics

• Measurment Configurations
• Understand Measurement Process
• Performing Measurement

The Measurement ribbon consists of the following groups.

• Import/Export: Using the Import and Export option you can configure the import and export setting of the measurement module. For more details refer, to Import and Export Settings.
• Reset All: Using the “Reset All” option you can reset parameters used for the measurement setup (scene, speaker mapping, mic mapping, and measurement session).
• Sound Settings: In the Sound Settings group you can configure Device Output Mapping, Generator, and Test Sound settings. For more details refer to Sound Settings.

The entire ribbon bar will not function once a measurement session is active, it will re-function after it ends since the settings made here do not affect an active measurement session.

 

Import and Export Settings

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• Import MM IR Setting
• Export MM IR Settings

Import MM IR Setting

The import menu allows you to import parameters available in the specified file.
Following are the parameters you can import.

• Chosen scene
• Device output mapping
• Configured speakers
• Configured microphones
• Defined measurement sequences

These settings can be imported individually or together. Only the selection of the sequence import forces the import of speakers and microphones to guarantee consistency.
The import for the device output mapping will throw a warning if the project does not match the original project.

Export MM IR Settings

The export allows you to export all setup-related parameters.
Following are the parameters you can export.

• Chosen scene
• Device output mapping
• Configured speakers
• Configured microphones
• Defined measurement sequences

These settings can be exported individually or together. Only the selection of the sequence export forces the export of speakers and microphones to guarantee consistency upon re-import.

Sound Settings

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In this group, you can configure Device Output Mapping, Generator, and Test Sound parameters. These menus are accessible during every step of the measurement preparation.

• Device Output Mapping: The device output mapping menu allows for the mapping of gain channels to device output channels.
• Generator: The generator menu is used to define parameters for the signal used in measurements. Using the drop-down option you can select Generator mode.
• Test Sound: The Test Sound menu is used to set the parameters for the test sound.

The generator menu is used to define parameters for the signal used in measurements. Using the drop-down option you can select Generator mode.

The generator supports the following mode.

• Synchronous (for synchronous IR measurements)
• Asynchronous (for asynchronous IR measurements)
• Recording

Synchronous Mode

The following parameters can be set in synchronous mode:

• Stimulus length: Duration of the signal in seconds used to measure.
• Silence after stimulus: Stop margin after end of playback, to capture the tail of the sweep signal also in very reverberant environments or over long distances. Takes decimal values.
• Number of repetitions: Number of measurement tools will be, used for average measurement.
• Gain: Playback gain in dBFS, only integers can be specified, and positive values will be correct to negative.
• Override start frequency: If checked, the value entered for “Start frequency override” takes precedence over individual loudspeaker settings on the speaker configuration tab
• Start frequency override: Lowest frequency of the sweep. Only enabled if Override start frequency is enabled.
• Stop frequency: Highest frequency of the sweep. The value will be hard limited to 1/2* sample rate.
  

Asynchronous Mode

The following parameters can be set in asynchronous mode:

• Stimulus length: Duration of the signal in seconds used to measure.
• Silence after stimulus: Stop margin after end of playback, to capture the tail of the sweep signal also in very reverberant environments or over long distances.
• Number of repetitions: Number of measurement tools will be used for average measurement.
• Gain: Playback gain in dBFS, only integers can be specified, positive values will be correct to negative
• Stimulus type: Choice between “Predefined” and “External”.
  

For the “External” Stimulus type, the following additional parameters can be set.

• Selected signal: Signal from the signal library.
• Export Stimulus: Opens an export dialog to export the signal for manual playback according to the parameters defined in this menu.
• Soundcard input: Selection of the soundcard input used for external stimulus tracking (the measurement on this channel will be used as a reference for the IR estimation). The channels specified here cannot be used as microphone input channels.
  

The default settings can always be recalled by clicking on Set to Default.
The Sample rate information is read-only. You can “Sound Card Configuration” to modify the sample rate.

The signal library folder for predefined stimulus signals can be set under  File > Options > General Settings > Predefined Stimulus Signals Folder.

The folder needs to contain a “PredefinedSignalsDescription.csv” file specifying the details of the files, and a folder each containing the wav files all required sampling rates:

The following parameters can be set in recording mode:

Recording Mode

Measurement signal length in seconds for pure recordings without signal generation. The maximum recording length is 60 seconds.