SimpleFreeFieldHRIR

Description

File:SimpleFreeFieldHRTF.png

This conventions essentially defines the setup used in the ARI, LISTEN, FIU, CIPIC, and other similar HRTF databases. The measurements are done at a constant distance in free field with a single excitation source assuming an omnidirectional loudspeaker. Human listeners are considered and thus, the number of receivers is two. Azimuth and elevation angles are varied and the tilt of the head is not considered during the measurement. The measured HRTFs are represented as FIR filters, with a single HRTF set of a listener per file. The SOFA conventions SimpleFreeFieldHRIR defines such a setup. It requires: General attributes: SOFAConventions: SimpleFreeFieldHRIR, Datatype: FIR, RoomType: free field, other general attributes... Data: The number of receivers is two, thus, the size of Data.IR is [M 2 N]. Only a single sampling rate for the file is allowed, thus SamplingRate is a scalar. Source: Source is in the origin of the setup and consists of a single emitter. SourcePosition: (0 0 0), SourceUp: (0 0 1), SourceView: (1 0 0), SourceRotation, and EmitterPosition: (0 0 0).

• Listener: The listener is in the measurement distance X (in meter) from the source, facing the source. ListenerPosition: (X 0 0), ListenerView: (0 0 0), ListenerUp: (X 0 1).
• Receivers: Two receivers (=ears) on a head with radius H (in meter): ReceiverPosition: (0 -H 0; 0 +H 0).
• The different azimuth and elevation angles of the measurement are described by the ListenerRotation as [M 3] matrix (in degrees). The coordinate type is “din9300”.

Parameters

Name	Default	Flags	Dimensions	Comment
GLOBAL_Conventions	SOFA	rm
GLOBAL_Version	0.3	rm
GLOBAL_SOFAConventions	SimpleFreeFieldHRIR	rm
GLOBAL_SOFAConventionsVersion	0.1	m
GLOBAL_APIName	*	rm		Insert the API Name here
GLOBAL_APIVersion	*	rm		Insert the API Version here
GLOBAL_ApplicationName		m
GLOBAL_ApplicationVersion		m
GLOBAL_AuthorContact		m
GLOBAL_License	No license provided, ask the author for permission	m
GLOBAL_Organization		m
GLOBAL_DatabaseName		m
GLOBAL_SubjectID		m
GLOBAL_RoomType	free field	m
GLOBAL_DataType	FIR	m
GLOBAL_History
GLOBAL_Comment
GLOBAL_DatabaseTimeCreated	*	m		will be updated when saving and not existing or empty
GLOBAL_DatabaseTimeModified	*	m		will be updated each time when saving
I	1	rm	I
I_LongName	singleton dimension	rm
R	2	rm	R
R_LongName	number of receivers	rm
E	1	rm	E
E_LongName	number of emitters	rm
N	-	m	N
N_LongName	time	m
N_Units	samples	m
M	-	m	M
M_LongName	number of measurements	rm
C	3	rm	C
C_LongName	coordinate triplet	rm
ListenerPosition	[1 0 0]	m	IC, MC
ListenerPosition_Type	cartesian	m
ListenerPosition_Unitsmeter		m
ListenerUp	[1.2 0 1]	m	IC, MC
ListenerUp_Type	cartesian	m
ListenerUp_Units	meter	m
ListenerView	[0 0 0]	m	IC, MC
ListenerView_Type	cartesian	m
ListenerView_Units	meter	m
ListenerRotation	[0 0 0]	m	IC, MC
ListenerRotation_Type	din9300	m
ListenerRotation_Units	degrees	m
ReceiverPosition	[0 -0.09 0; 0 0.09 0]	m	rCI, rCM
ReceiverPosition_Type	cartesian	m
ReceiverPosition_Units	meter	m
SourcePosition	[0 0 0]	m	IC, MC
SourcePosition_Type	cartesian	m
SourcePosition_Units	meter	m
SourceUp	[0 0 1]	m	IC, MC
SourceUp_Type	cartesian	m
SourceUp_Units	meter	m
SourceView	[1 0 0]	m	IC, MC
SourceView_Type	cartesian	m
SourceView_Units	meter	m
EmitterPosition	[0 0 0]	m	eCI, eCM
EmitterPosition_Type	cartesian	m
EmitterPosition_Units	meter	m
Data.IR	[1 1]	m	mRn
Data.SamplingRate	48000	m	I
Data.SamplingRate_Units	hertz	m

Legend:

• Name: the name of the metadata
  • An underscore (_): the metadata is an attribute
    • GLOBAL_: the metadata is a global attribute
    • X_Y: the metadata is an attribute Y of the variable X
  • No underscore: the metadata is a variable
  • Data.X: the metadata is structured within the data
• Default: default value for the metadata
  • An asterisk (*): special handling required, mentioned in the column Comment
• Flags:
  • r: read-only, must be the default value
  • m: mandatory, must be saved in the file
• Dimensions: dimensions of the metadata (see SOFA specifications for more explanations)
  • lower case: the variable size in that dimension determines the dimension size in the file
  • upper case: variable must be of that dimension (or one of these dimensions)