SimpleFreeFieldHRIR

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Description

This conventions essentially defines the setup used to measure HRTFs in free field. The measured HRTFs are represented as FIR filters, with a single HRTF set of a listener per file. We defined this conventions to describe data from databases like ARI, LISTEN, FIU, CIPIC, and others.

In SimpleFreeFieldHRIR version 0.2, we used ListenerRotation to describe the different measurement directions, and the source was assumed to be in the center of the measurement setup. This, however, limited the use of SimpleFreeFieldHRIR, thus, in version 0.4, we use SourcePosition to represent the different HRTF directions. By doing so, more complex data can be described where the tilt of the head is varied, or the listener is not exactly in the center of the measurement setup.

In SimpleFreeFieldHRIR version 0.4, the last version before AES69-2015, we adapted the conventions to SOFA 0.6. The most striking changes are:

  • Source has been renamed to Origin (in order to reduce the confusion with the object source)
  • SubjectID has been renamed to ListenerShortName (in order to be more consistent with the general naming of the metadata).

SimpleFreeFieldHRIR version 1.0 represents the current standardized convention set from AES69-2015.

Version 1.0

SimpleFreeFieldHRIR-0.3.png

This convention set essentially defines the setup used in the ARI, LISTEN, FIU, CIPIC, and other similar HRTF databases. The measurements are done in free field with a single excitation source assuming an omnidirectional loudspeaker. Human listeners are considered and thus, the number of receivers is two. Note that usually, only the apparent azimuth and elevation angles are provided and this information is modeled as the variation of the source position. This convention set can, however, also be used to describe more complex data where the tilt of the head is varied or the listener is not exactly in the center of the measurement setup. The measured HRTFs are represented as FIR filters, with a single HRTF set of a listener per file.

  • General attributes: SOFAConventions: SimpleFreeFieldHRIR, Datatype: FIR, RoomType: free field, other general attributes...
  • Listener: The listener is in the origin of the setup, facing in the direction of the y-axis. Thus, for default values, ListenerPosition=[0 0 0], ListenerView=[1 0 0], ListenerUp=[0 0 1], all given in cartesian coordinates.
  • Receivers: Two receivers (=ears) on a head with radius H (in meter, default: 0.09): ReceiverPosition=[0 -H 0; 0 +H 0].
  • Source: Source consists of a single emitter. For default values, EmitterPosition=[0 0 0] in cartesian coordinates. SourcePosition (in spherical coordinates!) varies corresponding to the different azimuth and elevation angles of the measurement directions. For default, SourcePosition=[0 0 1] (azimuth 0°, elevation 0°, distance 1 m). SourceUp and SourceView are not considered and optional.


Name Default Flags Dimensions Type Comment
GLOBAL:Conventions SOFA rm attribute
GLOBAL:Version 1.0 rm attribute
GLOBAL:SOFAConventions SimpleFreeFieldHRIR rm attribute This convention set is for HRIRs recorded under free-field conditions or other IRs created under conditions where room information is irrelevant
GLOBAL:SOFAConventionsVersion 1.0 rm attribute
GLOBAL:APIName rm attribute
GLOBAL:APIVersion rm attribute
GLOBAL:ApplicationName attribute
GLOBAL:ApplicationVersion attribute
GLOBAL:AuthorContact m attribute
GLOBAL:Comment attribute
GLOBAL:DataType FIR rm attribute
GLOBAL:History attribute
GLOBAL:License No license provided, ask the author for permission m attribute
GLOBAL:Organization m attribute
GLOBAL:References attribute
GLOBAL:RoomType free field m attribute
GLOBAL:Origin attribute
GLOBAL:DateCreated m attribute
GLOBAL:DateModified m attribute
GLOBAL:Title m attribute
ListenerPosition [0 0 0] m IC, MC double
ListenerPosition:Type cartesian m attribute
ListenerPosition:Units metre m attribute
ReceiverPosition [0 0.09 0; 0 -0.09 0] m rCI, rCM double
ReceiverPosition:Type cartesian m attribute
ReceiverPosition:Units metre m attribute
SourcePosition [0 0 1] m IC, MC double Source position is assumed to vary for different directions/positions around the listener
SourcePosition:Type spherical m attribute
SourcePosition:Units degree, degree, metre m attribute
EmitterPosition [0 0 0] m eCI, eCM double
EmitterPosition:Type cartesian m attribute
EmitterPosition:Units metre m attribute
GLOBAL:DatabaseName m attribute name of the database to which these data belong
GLOBAL:ListenerShortName m attribute ID of the subject from the database
ListenerUp [0 0 1] m IC, MC double
ListenerView [1 0 0] m IC, MC double
ListenerView:Type cartesian m attribute
ListenerView:Units metre m attribute
Data.IR [0 0] m mRn double
Data.SamplingRate 48000 m I double
Data.SamplingRate:Units hertz m attribute
Data.Delay [0 0] m IR, MR double

Old, deprecated versions

For historical reasons the older versions of the SimpleFreeFieldHRIR Convention are listed below.

Version 0.4 (deprecated)

SimpleFreeFieldHRIR-0.3.png

This conventions essentially defines the setup used in the ARI, LISTEN, FIU, CIPIC, and other similar HRTF databases. The measurements are done in free field with a single excitation source assuming an omnidirectional loudspeaker. Human listeners are considered and thus, the number of receivers is two. Note that usually, only the apparent azimuth and elevation angles are provided and this information is modeled as the variation of the source position. This conventions can, however, also be used to describe more complex data where the tilt of the head is varied or the listener is not exactly in the center of the measurement setup. The measured HRTFs are represented as FIR filters, with a single HRTF set of a listener per file.

  • General attributes: SOFAConventions: SimpleFreeFieldHRIR, Datatype: FIR, RoomType: free field, other general attributes...
  • Listener: The listener is in the origin of the setup, facing in the direction of the y-axis. Thus, for default values, ListenerPosition=[0 0 0], ListenerView=[1 0 0], ListenerUp=[0 0 1], all given in cartesian coordinates.
  • Receivers: Two receivers (=ears) on a head with radius H (in meter, default: 0.09): ReceiverPosition=[0 -H 0; 0 +H 0].
  • Source: Source consists of a single emitter. For default values, EmitterPosition=[0 0 0] in cartesian coordinates. SourcePosition (in spherical coordinates!) varies corresponding to the different azimuth and elevation angles of the measurement directions. For default, SourcePosition=[0 0 1] (azimuth 0°, elevation 0°, distance 1 m). SourceUp and SourceView are not considered and optional.


Name Default Flags Dimensions Type Comment
GLOBAL:Conventions SOFA rm attribute
GLOBAL:Version 0.6 rm attribute
GLOBAL:SOFAConventions SimpleFreeFieldHRIR rm attribute This convention set is for HRIRs recorded under free-field conditions or other IRs created under conditions where room information is irrelevant
GLOBAL:SOFAConventionsVersion 0.4 rm attribute
GLOBAL:APIName rm attribute
GLOBAL:APIVersion rm attribute
GLOBAL:ApplicationName attribute
GLOBAL:ApplicationVersion attribute
GLOBAL:AuthorContact m attribute
GLOBAL:Comment attribute
GLOBAL:DataType FIR rm attribute
GLOBAL:History attribute
GLOBAL:License No license provided, ask the author for permission m attribute
GLOBAL:Organization m attribute
GLOBAL:References attribute
GLOBAL:RoomType free field m attribute
GLOBAL:Origin attribute
GLOBAL:DateCreated m attribute
GLOBAL:DateModified m attribute
GLOBAL:Title m attribute
ListenerPosition [0 0 0] m IC, MC double
ListenerPosition:Type cartesian m attribute
ListenerPosition:Units meter m attribute
ReceiverPosition [0 -0.09 0; 0 0.09 0] m rCI, rCM double
ReceiverPosition:Type cartesian m attribute
ReceiverPosition:Units meter m attribute
SourcePosition [0 0 1] m IC, MC double Source position is assumed to vary for different directions/positions around the listener
SourcePosition:Type spherical m attribute
SourcePosition:Units degree, degree, meter m attribute
EmitterPosition [0 0 0] m eCI, eCM double
EmitterPosition:Type cartesian m attribute
EmitterPosition:Units meter m attribute
GLOBAL:DatabaseName m attribute name of the database to which these data belong
GLOBAL:ListenerShortName m attribute ID of the subject from the database
ListenerUp [0 0 1] m IC, MC double
ListenerView [1 0 0] m IC, MC double
ListenerView:Type cartesian m attribute
ListenerView:Units meter m attribute
Data.IR [1 1] m mRn double
Data.SamplingRate 48000 m I double
Data.SamplingRate:Units hertz m attribute
Data.Delay [0 0] m IR, MR double


Proposed for version 0.3 (deprecated)

SimpleFreeFieldHRIR-0.3.png

This conventions essentially defines the setup used in the ARI, LISTEN, FIU, CIPIC, and other similar HRTF databases. The measurements are done in free field with a single excitation source assuming an omnidirectional loudspeaker. Human listeners are considered and thus, the number of receivers is two. Note that usually, only the apparent azimuth and elevation angles are provided and this information is modeled as the variation of the source position. This conventions can, however, also be used to describe more complex data where the tilt of the head is varied or the listener is not exactly in the center of the measurement setup. The measured HRTFs are represented as FIR filters, with a single HRTF set of a listener per file.

  • General attributes: SOFAConventions: SimpleFreeFieldHRIR, Datatype: FIR, RoomType: free field, other general attributes...
  • Listener: The listener is in the origin of the setup, facing in the direction of the y-axis. Thus, for default values, ListenerPosition=[0 0 0], ListenerView=[1 0 0], ListenerUp=[0 0 1], all given in cartesian coordinates.
  • Receivers: Two receivers (=ears) on a head with radius H (in meter, default: 0.09): ReceiverPosition=[0 -H 0; 0 +H 0].
  • Source: Source consists of a single emitter. For default values, EmitterPosition=[0 0 0] in cartesian coordinates. SourcePosition (in spherical coordinates!) varies corresponding to the different azimuth and elevation angles of the measurement directions. For default, SourcePosition=[0 0 1] (azimuth 0°, elevation 0°, distance 1 m). SourceUp, SourceView, and SourceRotation are not considered and optional.
Name Default Flags Dimensions Type Comment
GLOBAL:Conventions SOFA rm attribute
GLOBAL:Version 0.5 rm attribute
GLOBAL:SOFAConventions SimpleFreeFieldHRIR rm attribute This conventions is for HRIRs recorded under free-field conditions or other IRs created under conditions where room information is irrelevant
GLOBAL:SOFAConventionsVersion 0.3 rm attribute
GLOBAL:APIName rm attribute
GLOBAL:APIVersion rm attribute
GLOBAL:ApplicationName m attribute
GLOBAL:ApplicationVersion m attribute
GLOBAL:AuthorContact m attribute
GLOBAL:Comment m attribute
GLOBAL:DataType FIR rm attribute
GLOBAL:History m attribute
GLOBAL:License No license provided, ask the author for permission m attribute
GLOBAL:Organization m attribute
GLOBAL:References m attribute
GLOBAL:RoomType free field m attribute
GLOBAL:Source m attribute
GLOBAL:TimeCreated m attribute
GLOBAL:TimeModified m attribute
GLOBAL:Title m attribute
ListenerPosition [0 0 0] m IC, MC double
ListenerPosition:Type cartesian m attribute
ListenerPosition:Units meter m attribute
ReceiverPosition [0 -0.09 0; 0 0.09 0] m rCI, rCM double
ReceiverPosition:Type cartesian m attribute
ReceiverPosition:Units meter m attribute
SourcePosition [0 0 1] m IC, MC double Source position is assumed to vary for different directions/positions around the listener
SourcePosition:Type spherical m attribute
SourcePosition:Units degree, degree, meter m attribute
EmitterPosition [0 0 0] m eCI, eCM double
EmitterPosition:Type cartesian m attribute
EmitterPosition:Units meter m attribute
GLOBAL:DatabaseName m attribute name of the database to which these data belong
GLOBAL:SubjectID m attribute ID of the subject from the database
ListenerUp [0 0 1] m IC, MC double
ListenerView [1 0 0] m IC, MC double
Data.IR [1 1] m mRn double
Data.SamplingRate 48000 m I double
Data.SamplingRate:Units hertz m attribute
Data.Delay [0 0] m IR, MR double


Version 0.2 (deprecated)

SimpleFreeFieldHRIR-0.2.png

This conventions essentially defines the setup used in the ARI, LISTEN, FIU, CIPIC, and other similar HRTF databases. The measurements are done 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.

  • General attributes: SOFAConventions: SimpleFreeFieldHRIR, Datatype: FIR, RoomType: free field, other general attributes...
  • Source: Source is in the origin of the setup and consists of a single emitter. For default values, SourcePosition: (0 0 0), and EmitterPosition: (0 0 0). SourceUp, SourceView, and SourceRotation are not considered and optional.
  • Listener: The listener is in the measurement distance X (in meter) from the source, facing the source. For default values, we consider a single distance X, thus, 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 DIN 9300.
Name Default Flags Dimensions Type Comment
GLOBAL_Conventions SOFA rm
GLOBAL_Version 0.4 rm
GLOBAL_SOFAConventions SimpleFreeFieldHRIR rm
GLOBAL_SOFAConventionsVersion 0.2 rm
GLOBAL_APIName rm Insert the API Name here
GLOBAL_APIVersion rm Insert the API Version here
GLOBAL_AuthorContact m
GLOBAL_License No license provided, ask the author for permission m
GLOBAL_Organization m
GLOBAL_RoomType free field m
GLOBAL_DataType FIR rm
GLOBAL_History m
GLOBAL_Source m
GLOBAL_Title m
GLOBAL_References m
GLOBAL_Comment m
GLOBAL_TimeCreated m will be updated when saving and not existing or empty
GLOBAL_TimeModified m will be updated each time when saving
GLOBAL_ApplicationName m
GLOBAL_ApplicationVersion m
GLOBAL_DatabaseName m
GLOBAL_SubjectID m
ListenerPosition [1 0 0] m IC, MC double
ListenerPosition_Type cartesian m
ListenerPosition_Units meter m
ListenerUp [0 0 1] m IC, MC double
ListenerView [-1 0 0] m IC, MC double
ListenerRotation [0 0 0] m IC, MC double
ListenerRotation_Type din9300 m
ListenerRotation_Units degrees m
ReceiverPosition [0 -0.09 0; 0 0.09 0] m rCI, rCM double
ReceiverPosition_Type cartesian m
ReceiverPosition_Units meter m
SourcePosition [0 0 0] m IC, MC double
SourcePosition_Type cartesian m
SourcePosition_Units meter m
EmitterPosition [0 0 0] m eCI, eCM double
EmitterPosition_Type cartesian m
EmitterPosition_Units meter m
Data.IR [1 1] m mRn double
Data.SamplingRate 48000 m I double
Data.SamplingRate_Units hertz m
Data.Delay [0 0] m IR, MR double


Version 0.1 (deprecated)

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