Applying Distance Effects

Currently the aviary is only occupied by a single chirping bird. In the last lesson you learned that moving the bird’s position caused its volume and frequency response to change due to Spatial’s distance effects system.  The degree to which distance effects impact sounds is something that you can manipulate, effectively allowing you to modify the physics of how sound propagates through space. This can have the effect of stretching or shrinking the acoustic environment around Objects. You’ll explore this by leaving the Bird Object in its current position, high up in the front of the Scene, but modify the distance effects to change how the sound is perceived within the listening environment.

  1. Open the Aviary Lesson 3 Scene in your assets folder and play the Scene.

    3.1.png

    You hear the bird chirping in front of you about 30 meters in the air. If you lower the bird back to ground level you’ll once again hear how the properties of volume and frequency are impacted. To get a baseline of the default distance effects are acting on the bird, raise and lower the bird’s height. Remember that you can double-click an Object to bring up the Object Manipulation Tool in the Canvas and then drag the blue arrow up or down to raise and lower the Z-axis.

    NOTE: if you have not downloaded the associated assets, please visit the Resources page in Lesson 1.

  2. Play the Scene and experiment with raising the Bird Object’s Z axis value between 0 and 50 meters, and then return it back to 30 meters.

    3.2.png


    Distance effects are only applied to Objects that are placed beyond the room boundary, so you should start to notice a change to the sound once the bird is raised above 4 meters, the highest speaker positions in the Spacemap.

    Having to repeatedly play the Scene can be cumbersome, so instead you can set it to loop.
     
  3. Select the Bird Object in the Inspector and in the Timing area, click the Loop checkbox.

    3.3.png


    By default the loop setting is set to infinite, so once you play the Scene, you’ll need to click the square Stop button in the transport or press the spacebar. This loop setting will be part of the published Scene. In a later lesson you’ll learn more about looping and other features to control how often a sound is heard for creative purposes, but for now looping the sound will make it easier for you to understand the changes to the distance effects you’ll be working with.

Understanding Default Distance Settings

The distance effects you’ve been hearing as you change the bird’s position are based on a default set of parameters designed to mimic how sound changes over distance in nature. By default a Basic preset is applied to Objects automatically. 

  1. With the Bird Object selected, scroll to the Distance Effect area in the Inspector.

    3.4.png


    Notice that the default position in the pull-down menu says Basic and that just below, a switch indicates the Basic preset is enabled. You can easily understand the impact of distance effects when they’re not being applied.

  2. Click the Enable switch so that distance effects are disabled, then play and listen to the Bird Object while changing its Z axis value, settling on 30 meters.

    3.5.png


    Notice that without distance effects, there’s no perception of how physics acts on a sound’s amplitude and frequency. Presets modify how amplitude and high frequencies are changed and they even add in reverberation to further enhance the sense of space.

  3. Re-enable distance effects and as the bird is playing, click the pull down menu to change the preset to Outdoor, then Indoor and back to Basic.

    3.6.png


    You can hear that each preset presents a different acoustic character. To see what’s different about the settings within each preset, you can look within the Advanced settings area.

  4. In the lower part of the Distance Effect area, click the Advanced disclosure triangle.

    3.7.png

    Now you see properties for Amplitude falloff, High Frequency Falloff, and Distance Reverb.

  5. Cycle through the presets once again and note the changes to the various properties.

    3.8.png

    You can see that each of these presets varies that amount of falloff for amplitude and high frequency. Falloff represents how much the amplitude or high frequency is subtracted from the sound as it gets further away from the Spacemap. The third property is reverb. This is applied to the Outdoor and Indoor presets as a way to give an added sense of space around the Object. 

Creating Custom Settings

In addition to Distance Effect presets, custom distance effect settings can be created. For the bird, try exaggerating the high frequency rolloff from the default Basic preset value. 

  1. Select the Basic preset and then change the High frequency falloff value to 3.0 and listen to the change.

    3.9.png

    Now it’s easier to feel that the bird is off in the distance. To give more of a sense of space, add some reverberation.
  2. Click the Distance reverb checkbox, raise the value to 3.75 and listen to the Scene.

    MISSING SCREENSHOT
     
    Now it’s believable that the bird is high up in the air!

    It’s possible to further modify the reverberation parameters. Try putting the bird into a bigger space.

  3. Below the Distance Reverb slider click the Advanced disclosure triangle.

    3.10.png


    Now you see adjustable properties for the reverb. The reverb and early reflection times are expressed as seconds, so adjusting these to higher values can create a broader sense of space.

  4. Change the reverb time to 4.0 and the early reflection time to .75

    3.11.png


    You can now get a more realistic sense of the space around the aviary.

    NOTE: Reverb requires more processing power. For Scenes with numerous Objects, care should be taken with the use of Reverb to prevent an overload on the deployment computer.



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