freqz

HRTF frequency response

Since R2024a

Syntax

[h,f] = freqz(s)

[h,f] = freqz(s,Name=Value)

freqz(___)

Description

[h,f] = freqz(s) returns the complex frequency response and the frequency vector of the first measurement of the HRTF data.

[h,f] = freqz(s,Name=Value) specifies options using one or more name-value arguments.

freqz(___) with no output arguments plots the frequency response.

Examples

Compute Frequency Response of HRTF Data

Read in a SOFA file containing HRTF measurements.

s = sofaread("ReferenceHRTF.sofa");

Use freqz to compute the frequency response of the first measurement for the first receiver.

[h,f] = freqz(s);

Call freqz with no output arguments to plot the frequency response of the first measurement for the first receiver.

freqz(s)

Compute Frequency Response in Specified Plane

Read in a SOFA file containing HRTF measurements.

s = sofaread("ReferenceHRTF.sofa");

Select the HRTF measurements in the sagittal plane at a lateral angle of 45 degrees. Plot the frequency responses of the second receiver for these measurements.

idx = findMeasurements(s,Plane="sagittal",PlaneOffsetAngle=45);
freqz(s,MeasurementIndex=idx,Receiver=2)
legend(Location="southeast")

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: freqz(s,NPoints=1024)

MeasurementIndex — Indices of measurements

1 (default) | vector of positive integers

Indices of measurements to use for the frequency response, specified as a vector of positive integers. The indices must correspond to measurements in the data of the SOFA object s.

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

Receiver — Indices of receivers

1 (default) | vector of positive integers

Indices of the receivers to use for the frequency response, specified as a vector of positive integers.

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

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

Output Arguments

h — Complex frequency response

N-by-M-by-R array

Complex frequency response of the HRTF data, returned as an N-by-M-by-R array, where:

• N is the length of the frequency response.

• M is the number of selected measurements defined by MeasurementIndex.

• R is the number of selected receivers defined by Receiver.

f — Frequencies

vector of length N

Frequencies in Hz corresponding to the frequency response, returned as a vector of length N, where N is the length of the frequency response.

Version History

Introduced in R2024a