interauralLevelDifference

Interaural level difference

Since R2024a

Syntax

ild = interauralLevelDifference(s)

ild = interauralLevelDifference(s,Name=Value)

[ild,f] = interauralLevelDifference(___)

[ild,f,ang] = interauralLevelDifference(___)

interauralLevelDifference(___)

Description

ild = interauralLevelDifference(s) computes the interaural level difference of the HRTF measurements in the horizontal plane at zero elevation. The interaural level difference is a binaural localization cue.

ild = interauralLevelDifference(s,Name=Value) specifies options using one or more name-value arguments.

[ild,f] = interauralLevelDifference(___) also returns the frequencies corresponding to the interaural level differences.

[ild,f,ang] = interauralLevelDifference(___) also returns the angles corresponding to the measurements.

interauralLevelDifference(___) with no output arguments plots the interaural level difference.

Examples

Compute Interaural Level Difference Using HRTF Data

Read in a SOFA file containing HRTF measurements.

s = sofaread("ReferenceHRTF.sofa");

Compute the interaural level difference of the HRTF data in the horizontal plane.

[ild,f,azi] = interauralLevelDifference(s);

Call interauralLevelDifference with no output arguments to plot the interaural level difference of the HRTF data in the horizontal plane.

interauralLevelDifference(s)

Input Arguments

s — SOFA object

SimpleFreeFieldHRIR object | SimpleFreeFieldHRSOS object | SimpleFreeFieldHRTF object

SOFA object, specified as one of the following objects.

• SimpleFreeFieldHRIR

• SimpleFreeFieldHRSOS

• SimpleFreeFieldHRTF

Name-Value Arguments

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: interauralLevelDifference(s, Plane="horizontal")

NPoints — Number of points in frequency response

positive integer

Number of points in the frequency response, specified as a positive integer. For SimpleFreeFieldHRIR objects, the default value is max(2048,L), where L is the length of the HRTF impulse responses. For SimpleFreeFieldHRSOS objects, the default value is 2048.

This argument does not apply to SimpleFreeFieldHRTF objects.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Plane — Plane

"horizontal" (default) | "median" | "sagittal"

Plane to compute the interaural level difference, 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.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

AngleTolerance — Angle tolerance

1 (default) | positive scalar

Angle tolerance in degrees, specified as a positive scalar. The function computes the interaural level difference of the measurements within the tolerance of the plane specified by Plane and PlaneOffsetAngle.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

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 interaural level difference. 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

ild — Interaural level difference

N-by-M matrix

Interaural level difference in dB, returned as an N-by-M matrix, where N is the number of points in the frequency response, and M is the number of specified measurements.

f — Frequencies

vector of length N

Frequencies in Hz corresponding to the interaural level differences, returned as a vector of length N, where N is the number of points in the frequency response.

ang — Angles

vector

Angles in degrees corresponding to the measurements used to compute the interaural level difference, 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.

More About

Interaural Level Difference

The interaural level difference is the difference in the power spectrum of the received sounds at the left and right ears. This provides a binaural localization cue at frequencies above approximately 1000 Hz because the head casts an acoustic shadow at higher frequencies.

At frequencies below 1500 Hz, the interauralTimeDifference provides a better binaural localization cue.

References

[1] Lee, Gyeong-Tae, Sang-Min Choi, Byeong-Yun Ko, and Yong-Hwa Park. "HRTF measurement for accurate sound localization cues." arXiv preprint arXiv:2203.03166 (2022).

Version History

Introduced in R2024a