You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
41 lines
2.5 KiB
41 lines
2.5 KiB
4 years ago
|
<META HTTP-EQUIV="Content-Type" CONTENT="text/html;charset=iso-8859-1">
|
||
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
||
|
|
<HTML><HEAD>
|
||
|
|
<META content="text/html; charset=iso-8859-1" http-equiv=Content-Type>
|
||
|
|
<META content="MSHTML 5.00.3103.1000" name=GENERATOR>
|
||
|
|
<STYLE></STYLE>
|
||
|
|
</HEAD>
|
||
|
|
<BODY bgColor=#fffbf0>
|
||
|
|
<DIV><FONT face=Arial size=2>
|
||
|
|
<H4><A name=_dx_sound_cones_dxaudio></A>Sound Cones</H4>
|
||
|
|
<P>A sound with no orientation has the same amplitude at a given distance in all
|
||
|
|
directions. A sound with an orientation is loudest in the direction of
|
||
|
|
orientation. The model that describes the loudness of the oriented sound is
|
||
|
|
called a sound cone. Sound cones are made up of an inside (or inner) cone and an
|
||
|
|
outside (or outer) cone. </P>
|
||
|
|
<P>At any angle within the inner cone, the volume of the sound is just what it
|
||
|
|
would be if there were no cone, after taking into account the basic volume of
|
||
|
|
the buffer, the distance from the listener, the listener's orientation, and so
|
||
|
|
on. </P>
|
||
|
|
<P>At any angle outside the outer cone, the normal volume is attenuated by a
|
||
|
|
factor set by the application. The outside cone volume is expressed in
|
||
|
|
hundredths of decibels and is a negative value, because it represents
|
||
|
|
attenuation from the default volume of 0.</P>
|
||
|
|
<P>Between the inner and outer cones is a zone of transition from the inside
|
||
|
|
volume to the outside volume. The volume decreases as the angle increases.</P>
|
||
|
|
<P>The following illustration shows the concept of sound cones.</P>
|
||
|
|
<P><IMG alt="" border=0
|
||
|
|
src="http://www.msdn.microsoft.com/library/psdk/directx/dx8_c/hh/directx8_c/images/soundcon.gif"></P>
|
||
|
|
<P>Every 3-D sound buffer has a sound cone, but by default a buffer behaves like
|
||
|
|
an omnidirectional sound source, because the outside volume is not attenuated,
|
||
|
|
and the inside and outside cone angles are 360 degrees. Unless the application
|
||
|
|
changes these values, the sound does not have any apparent orientation.</P>
|
||
|
|
<P>Designing sound cones properly can add dramatic effects to your application.
|
||
|
|
For example, you could position a sound source in the center of a room, setting
|
||
|
|
its orientation toward an open door in a hallway. Then set the angle of the
|
||
|
|
inside cone so that it extends to the width of the doorway, make the outside
|
||
|
|
cone a bit wider, and set the outside cone volume to inaudible. A listener
|
||
|
|
moving along the hallway will begin to hear the sound only when near the
|
||
|
|
doorway, and the sound will be loudest as the listener passes in front of the
|
||
|
|
open door.</P></FONT></DIV></BODY></HTML>
|