Figure contains an axes object. The axes object with title Horizontal Plane Energy-Time Curve. Receiver 1., xlabel Time (s), ylabel Azimuth (degrees) contains an object of type surface.

Compute Energy-Time Curve Using Interpolated HRTF Data

Open Live Script

Read in a SOFA file containing HRTF measurements.

s = sofaread("ReferenceHRTF.sofa");

Compute the energy-time curve of the HRTF data in the horizontal plane offset by 7 degrees of elevation. See how the returned value is empty because the SOFA file contains no measurements in the specified plane.

etc = energyTimeCurve(s,Plane="horizontal",PlaneOffsetAngle=7);
size(etc)

ans = 1×2

     0     0

Call energyTimeCurve with InterpolateHRTF set to true to compute the energy-time curve using interpolated HRTF measurements corresponding to 100 uniformly-spaced points in the specified plane.

etc = energyTimeCurve(s,Plane="horizontal",PlaneOffsetAngle=7,InterpolateHRTF=true);
size(etc)

ans = 1×2

   256   100

Input Arguments

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`s` — SOFA object
`SimpleFreeFieldHRIR` object

SOFA object, specified as a SimpleFreeFieldHRIR object.

Name-Value Arguments

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Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: energyTimeCurve(s,Plane="median")

`Receiver` — Indices of receivers
1 (default) | vector of positive integers

Indices of the receivers to use for the energy-time curve, specified as a vector of positive integers.

`Plane` — Plane
`"horizontal"` (default) | `"median"` | `"sagittal"`

Plane to compute the energy-time curve, specified as "horizontal", "median", or "sagittal".

Data Types: char | string

`PlaneOffsetAngle` — Plane offset angle
0 (default) | value in range [-90,90]

Plane offset angle in degrees, specified as a value in the range [-90,90]. This angle specifies the offset by which the Plane is shifted.

This argument only applies to the horizontal and sagittal planes. For the horizontal plane, the offset corresponds to the elevation angle. For the sagittal plane, the offset corresponds to the lateral angle.

`AngleTolerance` — Angle tolerance
1 (default) | positive scalar

Angle tolerance in degrees, specified as a positive scalar. The function computes the energy-time curve for the measurements within the tolerance of the plane specified by Plane and PlaneOffsetAngle.

`InterpolateHRTF` — Use interpolated HRTF measurements
`false` (default) | `true`

Use interpolated HRTF measurements, corresponding to 100 uniformly-spaced points in the specified plane, to compute the energy-time curve. Set this argument to true if the plane specified by Plane, PlaneOffsetAngle, and AngleTolerance does not contain a sufficient number of HRTF measurements. The function uses the bilinear interpolation method.

Data Types: logical

Output Arguments

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`etc` — Energy-time curve
vector of length M

Energy-time curve, returned as an N-by-M-by-R array, where:

N is the length of the impulse response.
M is the number of selected measurements.
R is the number of selected receivers defined by Receiver.

`t` — Time vector
vector of length N

Time vector in seconds corresponding to the impulse response, returned as a vector of length N, where N is the length of the impulse response.

`ang` — Angles
vector

Angles in degrees corresponding to the measurements used to compute the energy-time curve, returned as a vector. The interpretation of the angles depends on the specified Plane.

For the horizontal plane, the angles correspond to the azimuth.
For the median plane, the angles correspond to the elevation.
For the sagittal plane, the angles correspond to the polar angles.

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