OpenAL Specification and Reference
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Listener Object

The Listener Object defines various properties that affect processing of the sound for the actual output. The Listener is unique for an AL Context, and has no Name. By controlling the listener, the application controls the way the user experiences the virtual world, as the listener defines the sampling/pickup point and orientation, and other parameters that affect the output stream.

It is entirely up to the driver and hardware configuration, i.e. the installation of AL as part of the operating system and hardware setup, whether the output stream is generated for headphones or 2 speakers, 4.1 speakers, or other arrangements, whether (and which) HRTF's are applied, etc..

Listener Attributes

Several Source attributes also apply to Listener: e.g. POSITION, VELOCITY, GAIN. In addition, some attributes are listener specific.

Table 4. Listener Orientation

Name	Signature	Values	Default
ORIENTATION	fv	any except NaN	{ { 0.0f, 0.0f, -1.0f }, { 0.0f, 1.0f, 0.0f } }

Description: ORIENTATION is a pair of 3-tuples representing the 'at' direction vector and 'up' direction of the Object in Cartesian space. AL expects two vectors that are orthogonal to each other. These vectors are not expected to be normalized. If one or more vectors have zero length, implementation behavior is undefined. If the two vectors are linearly dependent, behavior is undefined.

Changing Listener Attributes

Listener attributes are changed using the Listener group of commands.

void Listener{n}{sifd}{v} ( enum paramName , T values );

Querying Listener Attributes

Listener state is maintained inside the AL implementation and can be queried in full. See Querying Object Attributes. The valid values for paramName are identical to the ones for the Listener* command.

void GetListener{sifd}v ( enum param , T * values );

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