Headphone Compensation Filters - ShanonPearce/ASH-IR-Dataset GitHub Wiki

Research into binaural simulations has shown that spectral colouration has the largest impact on the plausibility of binaural simulations [1]. One source of spectral colouration is the headphones used for binaural reproduction. A common design goal for headphone calibration is the diffuse-field target which minimises spectral colouration of stereo signals on headphones. Binaural measurements that have been diffuse-field equalised will be compatible with these types of headphones.

Although diffuse-field calibrated headphones are common, differences in frequency responses of different headphones are considerably large [2], [3], [4]. Individual headphone equalisation is therefore recommended to compensate for undesired spectral colouration introduced by the headphones and to remove the differences in frequency responses. As the binaural measurements in this dataset are diffuse-field equalised, headphones should be equalised to the diffuse-field target for compatibility in terms of timbral quality.

This dataset includes headphone compensation filters (HpCFs) for a wide range of commonly used headphones. The filters can be used to equalise individual headphones to the diffuse-field target response and compensate for undesired spectral colouration introduced by the headphones.

Headphones

Headphone manufacturers supported include AKG, Audeze, Audio-Technica, Beyerdynamic, HiFiMAN, Sennheiser, and many more. Headphone types supported include circumaural, in-ear, and on-ear headphones.

Filter Type

The HpCFs are minimum-phase FIRs with a filter length of 1024.

Format

The HpCFs are provided as single channel WAV files with a sampling rate of 44100Hz and a bit depth of 24 bits per sample.

Usage

The HpCFs can be used to correct the frequency response of the listener's headphones by convolving an audio stream with a HpCF. This requires IR Convolution software such as Equalizer APO.

A sample Equalizer APO configuration is provided below. A set of HpCF convolution templates for Equalizer APO are also provided in the E-APO_Configs folder.

Channel: all

Convolution: ..\HpCFs\HpCF_<selected_headphone>.wav

Naming Convention

The HpCF file names follow the naming convention below.

HpCF_<manufacturer>_<headphone_model>_<alternative>.WAV

Alternative HpCFs are included for headphones that were measured in multiple datasets and are indicated by a letter from A to Z in the alternative field. Averaged HpCFs are provided for each applicable headphone and are indicated by Avg in the alternative field. Magnitude response plots are also provided for each HpCF to allow for easy comparison of different alternatives.

Compatibility Filters

Filters for compatibility with in-ear and on-ear headphones are provided in the Compatibility_Filters folder. The filter labelled Compatibility_In-Ear_Headphones should be used with in-ear headphones and the filter labelled Compatibility_On-Ear_Headphones should be used with on-ear headphones to provide compatibility with the BRIRs. A compatibility filter is not required for circumaural (over-ear) headphones as the BRIRs in this dataset have already been made compatible with circumaural headphones through equalisation.

Additional Filters

The filter labelled Improved_Diffuse-Field_EQ in the HpCFs\Additional_Filters folder is provided for all headphones as an optional improvement to the diffuse-field equalisation target. The filter can be used together with any of the individual HpCFs by adding an additional 'convolution' command in Equalizer APO and navigating to the filter.

The filter labelled Diffuse-Field_EQ_for_In-Ear_Headphones is a generalised equalisation filter that is suitable for use with in-ear headphones that are not diffuse-field calibrated.

The filter labelled Room_Target_Inverse is an inverse filter that can be used to remove the smooth downward slope that was applied to the rooms. This filter is recommended for headphones that are equalised to the Harman target curve or for users intending to apply their own preferred room target curve.

Measurements

The HpCFs in this dataset were created using headphone impulse responses and frequency response plots from multiple data sources including HRIR datasets [5], [6], headphone measurement databases [7], and personal headphone measurements.

References

[1] Lindau, A.; Hohn, T. and Weinzierl, S.: "Binaural resynthesis for comparative studies of acoustical environments.", Proc. of the 122nd AES Conv., Vienna, preprint no. 7032, 2007

[2] Sank, J. R.: "Improved Real-Ear Tests for Stereophones.", J. Audio Eng. Soc., 28(4), pp. 206-218, 1980

[3] Theile, G.: "On the Standardization of the Frequency Response of High-Quality Studio Headphones.", J. Audio Eng. Soc., 34(12), pp. 956-969, 1986

[4] Møller, H. et al.: "Design Criteria for Headphones.", J. Audio Eng. Soc., 43(4), pp. 218-232, 1995

[5] B. Fabian, “The FABIAN head-related transfer function data base,” depositonce, 2017 [Dataset]. Available: https://doi.org/10.14279/depositonce-5718

[6] B. Bernschutz, "Spherical Far-Field HRIR Compilation of the Neumann KU100," th-koeln, 2015 [Online]. Available: http://audiogroup.web.th-koeln.de/ku100hrir.html

[7] "measurements", DIY-Audio-Heaven, 2020. [Online]. Available: https://diyaudioheaven.wordpress.com/headphones/measurements