FreeFieldDirectivityTF

FreeFieldDirectivityTF SOFA convention

Since R2023b

Description

The FreeFieldDirectivityTF object stores SOFA data following the FreeFieldDirectivityTF convention. This convention stores directivities of acoustic sources (for example, instruments, loudspeakers, singers, and talkers) in the frequency domain for single or multiple measurements (for example, musical notes or playing styles). It considers musical notes as a parameter directly addressing musical instruments and singers. The measurements are performed in the free field with a single source that is surrounded by receivers. The measured data is represented as complex frequency-domain transfer functions (TF).

Use sofaread and sofawrite to read and write SOFA files with this convention.

Creation

Create a FreeFieldDirectivityTF object using sofaconvention.

s = sofaconvention("FreeFieldDirectivityTF");

Properties

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Data

`FrequencyResponse` — Frequency response
`0` (default) | M-by-R-by-N array

Measurements in frequency response form, specified as a complex M-by-R-by-N array, where M is the number of measurements, R is the number of receivers, and N is the frequency response length.

`FrequencyVector` — Frequency vector
1 (default) | vector

Frequency vector, in hertz, corresponding to the frequency response, specified as a vector.

`DataType` — Type of data
`"TF"`

This property is read-only.

Type of data in the file, returned as a string.

Listener

`ListenerPosition` — Listener position
`[0 0 0]` (default) | 1-by-3 matrix | M-by-3 matrix

Listener position in Cartesian, spherical, or spherical harmonics coordinates, specified as a 1-by-3 or M-by-3 matrix, where M is the number of measurements.

For more information, see Spatial Data Representations.

`ListenerPositionType` — Listener position type
`"cartesian"` (default) | `"spherical"` | `"spherical harmonics"`

Listener position type, specified as "cartesian", "spherical", or "spherical harmonics".

`ListenerPositionUnits` — Listener position units
`"meter"` | `"degree, degree, meter"`

This property is read-only.

Listener position units, returned as "meter" if ListenerPositionType is "cartesian" or "spherical harmonics". If ListenerPositionType is "spherical", the units are returned as "degree, degree, meter".

`ListenerView` — Listener view direction
`[1 0 0]` (default) | 1-by-3 matrix | M-by-3 matrix

Listener view direction, specified as a 1-by-3 or M-by-3 matrix, where M is the number of measurements. This property defines the direction of the positive x-axis of the local listener coordinate system.

`ListenerViewType` — Listener view type
`"cartesian"` (default) | `"spherical"`

Listener view type, specified as "cartesian" or "spherical".

`ListenerViewUnits` — Listener view units
`"meter"` | `"degree, degree, meter"`

This property is read-only.

Listener view units, returned as "meter" if ListenerViewType is "cartesian" or "degree, degree, meter" if ListenerViewType is "spherical".

`ListenerUp` — Listener up direction
`[0 0 1]` (default) | 1-by-3 matrix | M-by-3 matrix

Listener up direction, specified as a 1-by-3 or M-by-3 matrix, where M is the number of measurements. This property defines the direction of the positive z-axis of the local listener coordinate system.

Receiver

`ReceiverPosition` — Receiver positions
`[0 0 0]` (default) | 1-by-3 matrix | R-by-3 matrix | R-by-3-by-M array

Receiver positions in Cartesian coordinates, spherical coordinates, or spherical harmonics, specified as a 1-by-3 matrix, R-by-3 matrix, or R-by-3-by-M array, where M is the number of measurements. If ReceiverPositionType is "cartesian" or "spherical", R is the number of receivers. If ReceiverPositionType is "spherical harmonics", R is the number of spherical-harmonic coefficients.

For more information, see Spatial Data Representations.

`ReceiverPositionType` — Receiver position type
`"spherical"` (default) | `"cartesian"` | `"spherical harmonics"`

Receiver position type, specified as "cartesian", "spherical", or "spherical harmonics".

`ReceiverPositionUnits` — Receiver position units
`"meter"` | `"degree, degree, meter"`

This property is read-only.

Receiver position units, returned as "meter" if ReceiverPositionType is "cartesian" or "spherical harmonics". If ReceiverPositionType is "spherical", the units are returned as "degree, degree, meter".

Source

`SourcePosition` — Source position
`[0 0 1]` (default) | 1-by-3 matrix | M-by-3 matrix

Source position in Cartesian or spherical coordinates, specified as a 1-by-3 or M-by-3 matrix, where M is the number of measurements.

For more information, see Spatial Data Representations.

`SourcePositionReference` — Description of spatial reference of source
`""` (default) | string

Description of the spatial reference of the source position, specified as a string (for example, "The bell" for a trumpet or "On the front plate between the low- and mid/high-frequency unit" for a loudspeaker). This property provides a reference across different sources.

`SourcePositionType` — Source position type
`"cartesian"` (default) | `"spherical"`

Source position type, specified as "cartesian" or "spherical".

`SourcePositionUnits` — Source position units
`"meter"` | `"degree, degree, meter"`

This property is read-only.

Receiver position units, returned as "meter" if SourcePositionType is "cartesian" or "degree, degree, meter" if SourcePositionType is "spherical".

`SourceView` — Source view direction
`[1 0 0]` (default) | 1-by-3 matrix | M-by-3 matrix

Source view direction, specified as a 1-by-3 or M-by-3 matrix, where M is the number of measurements. This property defines the direction of the positive x-axis of the local source coordinate system.

`SourceViewType` — Source view type
`"cartesian"` (default) | `"spherical"`

Source view type, specified as "cartesian" or "spherical".

`SourceViewUnits` — Source view units
`"meter"` | `"degree, degree, meter"`

This property is read-only.

Source view units, returned as "meter" if SourceViewType is "cartesian" or "degree, degree, meter" if SourceViewType is "spherical".

`SourceViewReference` — Description of spatial reference of source view
`""` (default) | string

Description of the spatial reference of the source view, specified as a string (for example, "Viewing direction of the bell" for a trumpet or "Perpendicular to the front plate" for a loudspeaker). This property provides a reference across different sources.

`SourceUp` — Source up direction
`[0 0 1]` (default) | 1-by-3 matrix | M-by-3 matrix

Source up direction, specified as a 1-by-3 or M-by-3 matrix, where M is the number of measurements. This property defines the direction of the positive z-axis of the local source coordinate system.

`SourceUpReference` — Description of spatial reference of source up direction
`""` (default) | string

Description of the spatial reference of the source up direction, specified as a string (for example, "Along the keys, keys up" for a trumpet or "Perpendicular to the top plate" for a loudspeaker). This property provides a reference across different sources.

`SourceManufacturer` — Source manufacturer
`""` (default) | string

Source manufacturer, specified as a string.

`SourceType` — Description of acoustic source
`""` (default) | string

Description of the acoustic source, specified as a string (for example, "Violin", "Singer", or "2-way loudspeaker").

`SourceTuningFrequency` — Source tuning frequency (hertz)
`0` (default) | numeric scalar

Source tuning frequency, in hertz, to which the musical instrument is tuned corresponding to the note A4 (MIDI note number 64), specified as a numeric scalar.

Emitter

`EmitterPosition` — Emitter positions
`[0 0 0]` (default) | 1-by-3 matrix | E-by-3 matrix | E-by-3-by-M array

Emitter positions in Cartesian coordinates, spherical coordinates, or spherical harmonics, specified as a 1-by-3 matrix, E-by-3 matrix, or E-by-3-by-M array, where M is the number of measurements. If EmitterPositionType is "cartesian" or "spherical", E is the number of emitters. If EmitterPositionType is "spherical harmonics", E is the number of spherical-harmonic coefficients.

For more information, see Spatial Data Representations.

`EmitterPositionType` — Emitter position type
`"cartesian"` (default) | `"spherical"`

Emitter position type, specified as "cartesian" or "spherical".

`EmitterPositionUnits` — Emitter position units
`"meter"` | `"degree, degree, meter"`

This property is read-only.

Emitter position units, returned as "meter" if EmitterPositionType is "cartesian" or "degree, degree, meter" if EmitterPositionType is "spherical".

`EmitterDescription` — General emitter description
`""` (default) | string

General emitter description, specified as a string.

`EmitterDescriptions` — Descriptions of each emitter
empty array (default) | M-by-1 string array | E-by-1 string array | M-by-1 cell array of character strings | E-by-1 cell array of character strings

Descriptions of each emitter, specified as an M-by-1 or E-by-1 string array or M-by-1 or E-by-1 cell array of character strings, where M is the number of measurements and E is the number of emitters.

Room

`RoomType` — Room type
`"free field"` (default) | string

Type of room used to perform the measurements, specified as a string.

Metadata

`Musician` — Description of musician
`""` (default) | string

Description of musician, such as position or behavior, specified as a string (for example, "artificial excitation by R2D2").

`SOFAConventions` — Name of SOFA convention
`"FreeFieldDirectivityTF"`

This property is read-only.

Name of the SOFA convention, returned as a string.

`DatabaseName` — Name of database
`""` (default) | string

Name of the database that this data belongs to, specified as a string.

`Version` — Version of specifications
`"2.1"` (default) | string

This property is read-only.

Version of the SOFA AES69 specifications, returned as a string of the format "x.y" where x is the version major and y is the version minor.

`APIName` — Name of API
`"Audio Toolbox"` (default) | string

This property is read-only.

Name of the API that created or edited the SOFA file, returned as a string.

`APIVersion` — Version of API
`"1.0"` (default) | string

This property is read-only.

Version of the API that created or edited the SOFA file, returned as a string of the format "x.y" or "x.y.z" where x is the version major and y and z are the version minors.

`SOFAConventionsVersion` — Version of convention set
`"1.1"` (default) | string

This property is read-only.

Version of the SOFA AES69 convention set, returned as a string of the format "x.y" where x is the version major and y is the version minor.

`Title` — Title
`""` (default) | string

Title containing a succinct description of the file contents, specified as a string.

`AuthorContact` — Contact information of author
`""` (default) | string

Contact information of the author (for example, an email address), specified as a string.

`Organization` — Name of organization
`""` (default) | string

Name of the organization of the author, specified as a string.

`License` — Legal license
`""` (default) | string

Legal license under which the data is provided, specified as a string.

`ApplicationName` — Name of application
`"Audio Toolbox"` (default) | string

Name of the application that created or edited the file, specified as a string.

`ApplicationVersion` — Version of application
`"3.0.0"` (default) | string

Version of the application that created or edited the file, specified as a string.

`Comment` — Comment
`""` (default) | string

Comment that can contain miscellaneous information about the data or methods used to produce the data, specified as a string.

`History` — History
`""` (default) | string

History defining the audio trail for modifications to the original data, specified as a string.

`References` — References
`""` (default) | string

Published or web-based references that describe the data or the methods used to produce the data, specified as a string.

`Origin` — Origin
`""` (default) | string

Origin, specified as a string representing the method used for creating the original data. In the case of model-generated data, the origin should name the model and its version. In the case of observed or measured data, the origin should characterize the data and, where possible, name the measurement method.

`DateCreated` — Date created
string

This property is read-only.

Date and time of the creation of the file, returned as a string in ISO 8601 format "YYYY-MM-DD hh:mm:ss". This property is set when a new file is created.

`DateModified` — Date modified
string

This property is read-only.

Date and time of the last file modification, returned as a string in ISO 8601 format "YYYY-MM-DD hh:mm:ss". This property is updated when a file is saved.

Object Functions

`write`	Write SOFA file
`validate`	Validate SOFA data

Examples

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Create FreeFieldDirectivityTF SOFA File

Open Live Script

Create a SOFA template object following the FreeFieldDirectivityTF convention.

s = sofaconvention("FreeFieldDirectivityTF");

Generate mock frequency response data to store in the file. Initialize the FrequencyResponse property to store 512-point frequency responses for 25 measurements of a single receiver. Use freqz to get the complex frequency responses from random Butterworth filters.

M = 25;
R = 1;
N = 512;
s.FrequencyResponse = complex(zeros(M,R,N));
fs = 44100;

for m = 1:M
    [b,a] = butter(5,rand);
    [h,f] = freqz(b,a,N,fs);
    s.FrequencyResponse(m,1,:) = h;
end

s.FrequencyVector = f;

Save the data to a SOFA file.

sofawrite("mockFreqResponseData.sofa",s);

More About

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Spatial Data Representations

In this SOFA convention, you can represent spatial data using Cartesian or spherical coordinate systems with spatially discrete representations. Alternatively, you can represent spatial data with a continuous representation using spherical harmonics.

Each spatial representation stores the position data in numerical triplets (for example, [0 0 0]).

Cartesian coordinates contain three orthogonal linear values in the format [x y z]. The units of the values are meters.
Spherical coordinates contain angular values for azimuth and elevation and a linear value for the radius in the format [azimuth elevation radius]. The azimuth angle, in degrees, must be in the range [0, 360). The elevation angle, in degrees, must be in the range [-90, 90]. The units of the linear radius are meters.
The spatially continuous representation uses the spatial frequency domain represented by a finite series of spherical harmonics. The position data stores the real-valued spherical-harmonic coefficients in Ambisonic Channel Number (ACN) order. For spherical harmonics, only the third element of the triplet is relevant.
The number of spherical-harmonic coefficients N defines the highest spherical-harmonic order L, where N=(L+1)².

Version History

Introduced in R2023b

FreeFieldDirectivityTF

Description

Creation

Properties

Data

FrequencyResponse — Frequency response 0 (default) | M-by-R-by-N array

FrequencyVector — Frequency vector 1 (default) | vector

DataType — Type of data "TF"

Listener

ListenerPosition — Listener position [0 0 0] (default) | 1-by-3 matrix | M-by-3 matrix

ListenerPositionType — Listener position type "cartesian" (default) | "spherical" | "spherical harmonics"

ListenerPositionUnits — Listener position units "meter" | "degree, degree, meter"

ListenerView — Listener view direction [1 0 0] (default) | 1-by-3 matrix | M-by-3 matrix

ListenerViewType — Listener view type "cartesian" (default) | "spherical"

ListenerViewUnits — Listener view units "meter" | "degree, degree, meter"

ListenerUp — Listener up direction [0 0 1] (default) | 1-by-3 matrix | M-by-3 matrix

Receiver

ReceiverPosition — Receiver positions [0 0 0] (default) | 1-by-3 matrix | R-by-3 matrix | R-by-3-by-M array

ReceiverPositionType — Receiver position type "spherical" (default) | "cartesian" | "spherical harmonics"

ReceiverPositionUnits — Receiver position units "meter" | "degree, degree, meter"

Source

SourcePosition — Source position [0 0 1] (default) | 1-by-3 matrix | M-by-3 matrix

SourcePositionReference — Description of spatial reference of source "" (default) | string

SourcePositionType — Source position type "cartesian" (default) | "spherical"

SourcePositionUnits — Source position units "meter" | "degree, degree, meter"

SourceView — Source view direction [1 0 0] (default) | 1-by-3 matrix | M-by-3 matrix

SourceViewType — Source view type "cartesian" (default) | "spherical"

SourceViewUnits — Source view units "meter" | "degree, degree, meter"

SourceViewReference — Description of spatial reference of source view "" (default) | string

SourceUp — Source up direction [0 0 1] (default) | 1-by-3 matrix | M-by-3 matrix

SourceUpReference — Description of spatial reference of source up direction "" (default) | string

SourceManufacturer — Source manufacturer "" (default) | string

SourceType — Description of acoustic source "" (default) | string

SourceTuningFrequency — Source tuning frequency (hertz) 0 (default) | numeric scalar

Emitter

EmitterPosition — Emitter positions [0 0 0] (default) | 1-by-3 matrix | E-by-3 matrix | E-by-3-by-M array

EmitterPositionType — Emitter position type "cartesian" (default) | "spherical"

EmitterPositionUnits — Emitter position units "meter" | "degree, degree, meter"

EmitterDescription — General emitter description "" (default) | string

EmitterDescriptions — Descriptions of each emitter empty array (default) | M-by-1 string array | E-by-1 string array | M-by-1 cell array of character strings | E-by-1 cell array of character strings

Room

RoomType — Room type "free field" (default) | string

Metadata

Musician — Description of musician "" (default) | string

SOFAConventions — Name of SOFA convention "FreeFieldDirectivityTF"

DatabaseName — Name of database "" (default) | string

Version — Version of specifications "2.1" (default) | string

APIName — Name of API "Audio Toolbox" (default) | string

APIVersion — Version of API "1.0" (default) | string

SOFAConventionsVersion — Version of convention set "1.1" (default) | string

Title — Title "" (default) | string

AuthorContact — Contact information of author "" (default) | string

Organization — Name of organization "" (default) | string

License — Legal license "" (default) | string

ApplicationName — Name of application "Audio Toolbox" (default) | string

ApplicationVersion — Version of application "3.0.0" (default) | string

Comment — Comment "" (default) | string

History — History "" (default) | string

References — References "" (default) | string

Origin — Origin "" (default) | string

DateCreated — Date created string

DateModified — Date modified string

Object Functions

Examples

Create FreeFieldDirectivityTF SOFA File

More About

Spatial Data Representations

Version History

See Also

External Websites

`FrequencyResponse` — Frequency response
`0` (default) | M-by-R-by-N array

`FrequencyVector` — Frequency vector
1 (default) | vector

`DataType` — Type of data
`"TF"`

`ListenerPosition` — Listener position
`[0 0 0]` (default) | 1-by-3 matrix | M-by-3 matrix

`ListenerPositionType` — Listener position type
`"cartesian"` (default) | `"spherical"` | `"spherical harmonics"`

`ListenerPositionUnits` — Listener position units
`"meter"` | `"degree, degree, meter"`

`ListenerView` — Listener view direction
`[1 0 0]` (default) | 1-by-3 matrix | M-by-3 matrix

`ListenerViewType` — Listener view type
`"cartesian"` (default) | `"spherical"`

`ListenerViewUnits` — Listener view units
`"meter"` | `"degree, degree, meter"`

`ListenerUp` — Listener up direction
`[0 0 1]` (default) | 1-by-3 matrix | M-by-3 matrix

`ReceiverPosition` — Receiver positions
`[0 0 0]` (default) | 1-by-3 matrix | R-by-3 matrix | R-by-3-by-M array

`ReceiverPositionType` — Receiver position type
`"spherical"` (default) | `"cartesian"` | `"spherical harmonics"`

`ReceiverPositionUnits` — Receiver position units
`"meter"` | `"degree, degree, meter"`

`SourcePosition` — Source position
`[0 0 1]` (default) | 1-by-3 matrix | M-by-3 matrix

`SourcePositionReference` — Description of spatial reference of source
`""` (default) | string

`SourcePositionType` — Source position type
`"cartesian"` (default) | `"spherical"`

`SourcePositionUnits` — Source position units
`"meter"` | `"degree, degree, meter"`

`SourceView` — Source view direction
`[1 0 0]` (default) | 1-by-3 matrix | M-by-3 matrix

`SourceViewType` — Source view type
`"cartesian"` (default) | `"spherical"`

`SourceViewUnits` — Source view units
`"meter"` | `"degree, degree, meter"`

`SourceViewReference` — Description of spatial reference of source view
`""` (default) | string

`SourceUp` — Source up direction
`[0 0 1]` (default) | 1-by-3 matrix | M-by-3 matrix

`SourceUpReference` — Description of spatial reference of source up direction
`""` (default) | string

`SourceManufacturer` — Source manufacturer
`""` (default) | string

`SourceType` — Description of acoustic source
`""` (default) | string

`SourceTuningFrequency` — Source tuning frequency (hertz)
`0` (default) | numeric scalar

`EmitterPosition` — Emitter positions
`[0 0 0]` (default) | 1-by-3 matrix | E-by-3 matrix | E-by-3-by-M array

`EmitterPositionType` — Emitter position type
`"cartesian"` (default) | `"spherical"`

`EmitterPositionUnits` — Emitter position units
`"meter"` | `"degree, degree, meter"`

`EmitterDescription` — General emitter description
`""` (default) | string

`EmitterDescriptions` — Descriptions of each emitter
empty array (default) | M-by-1 string array | E-by-1 string array | M-by-1 cell array of character strings | E-by-1 cell array of character strings

`RoomType` — Room type
`"free field"` (default) | string

`Musician` — Description of musician
`""` (default) | string

`SOFAConventions` — Name of SOFA convention
`"FreeFieldDirectivityTF"`

`DatabaseName` — Name of database
`""` (default) | string

`Version` — Version of specifications
`"2.1"` (default) | string

`APIName` — Name of API
`"Audio Toolbox"` (default) | string

`APIVersion` — Version of API
`"1.0"` (default) | string

`SOFAConventionsVersion` — Version of convention set
`"1.1"` (default) | string

`Title` — Title
`""` (default) | string

`AuthorContact` — Contact information of author
`""` (default) | string

`Organization` — Name of organization
`""` (default) | string

`License` — Legal license
`""` (default) | string

`ApplicationName` — Name of application
`"Audio Toolbox"` (default) | string

`ApplicationVersion` — Version of application
`"3.0.0"` (default) | string

`Comment` — Comment
`""` (default) | string

`History` — History
`""` (default) | string

`References` — References
`""` (default) | string

`Origin` — Origin
`""` (default) | string

`DateCreated` — Date created
string

`DateModified` — Date modified
string