AVAS Tab

This window enables you to render Audible Vehicle Alert Sounds (AVAS) for electric vehicles. As electric vehicles are very quiet at low speed, AVAS are emitted by the vehicle to warn pedestrians and cyclists that a car is approaching. Once an AVAS is designed, this tab enables you to simulate how the AVAS will sound inside the vehicle.

The AVAS sound menu enables you to select an AVAS from the database. The toggle to the left of the menu enables you to start and stop playback of the chosen AVAS sound.

The Vehicle cabin filter menu enables you to select a cabin filter. These filters simulate the acoustic transfer function of the cabin. You may choose No cabin filter to hear the AVAS with no additional filtering.

The Speaker position menu enables you to define the position of the AVAS speaker. Usually, this speaker is at the front or rear of the vehicle.

The Speaker bandwidth controls enable you to simulate the bandwidth of the target speaker used to render the AVAS outside the vehicle, and assess the perception of the designed AVAS inside the vehicle. The lower (Fmin) and upper (Fmax) limits of the bandwidth are adjustable in real-time. Click the triangle next to the value you want to modify, and drag the pointer up or down to raise or lower the value.

The graph to the right of the menu displays the changing spectrum of the sound while it is playing.

AVAS Configuration File

The sounds in the menu, available cabin filters, speaker positions, and default bandwidth values are predefined in the configuration file AVAS.cfg, which is located in the located in the C:\ProgramData\Ansys\v242\Acoustics\CSS\Configuration files folder.

#########################################
# AVAS configuration file
#########################################

# AVAS SOUND FILES

AVAS1           : AVAS future sporty windy_loop.wav
NameAVAS1       : Sporty

AVAS2           : AVAS Iceflow 2 Genesis.wav
NameAVAS2       : Ice flow

AVAS3           : AVAS motor futurist Genesis_loop.wav
NameAVAS3       : Future

# cabin info
Cabin1          : Sedan
Cabin2          : City car
Cabin3          : No cabin filter

# position info
NamePosition1   : front
AnglePosition1  : 10
NamePosition2   : rear 
AnglePosition2  : 170

# filter info  (cabin1- position1, cabin1-position2, cabin2-position1, cabin2-position2....)
Filter1 : 0.001062 -0.000122 -0.000873 -1.368204 0.511351 1. -1.694177 0.763048 -1.91166 0.920043 1. -1.919359 0.930642 -1.966965 0.967524
Filter2 : 0.001174 -0.001254 0.000135 -1.446627 0.643941 1. -1.597527 0.713881 -1.936779 0.938102 1. -1.924125 0.93577 -1.934713 0.938229
Filter3 : 0.002172 -0.001805 0.000039 -1.508768 0.718884 1. -1.703491 0.771753 -1.943691 0.945092 1. -1.955234 0.961496 -1.955199 0.960034
Filter4 : 0.001885 -0.002754 0.001438 -1.463308 0.651491 1. -1.813701 0.826135 -1.980582 0.9809 1. -1.92089 0.922978 -1.981041 0.982742 

# speaker info
Fmin            : 100
Fmax            : 15000

#########################################

The fields in the AVAS.cfg file are defined as follows:

AVAS#: The filename of the sound file to be used for that number item in the AVAS sound menu.
NameAVAS#: The name displayed for that number item in the AVAS sound menu.
Note: The default AVAS.cfg file only contains three AVAS/NameAVAS pairs. If more than three sounds are needed, add more appropriately-numbered pairs to the file.
Cabin#: Names displayed for the items available in the Vehicle cabin filter menu.
NamePosition#: Name displayed for that number item in the Speaker position menu
AnglePosition#: Angle in degrees for that number item in the Speaker position menu. (0° is directly in front of the listener.)
Note: You cannot add more positions to the AVAS.cfg file.
Filter#: The filter coefficients below correspond to a cascade of biquad filters, each biquad having 5 coefficients. The number of coefficients for the filters must be a multiple of 5. The 5 biquad coefficients are a0, a1, a2, b1, and b2 defined by:
Y[n] = a0.X[n] + a1X[n-1]+ a2.X[n-2]- b1.Y[n-1]-b2.Y[n-2]

Note: You cannot add more filters to the AVAS.cfg file. You may modify the filter coefficients if you desire.
Fmin: Default lower limit for the target speaker bandwidth.
Fmax: Default upper limit for the target speaker bandwidth.