Nonlinear distortion reduction in sound zones by constraining individual loudspeaker control effort

TY - JOUR

T1 - Nonlinear distortion reduction in sound zones by constraining individual loudspeaker control effort

AU - Ma, Xiaohui

AU - Hegarty, Patrick J.

AU - Jørgensen, Kristoffer Foldager

AU - Larsen, Jakob Juul

PY - 2019/9

Y1 - 2019/9

N2 - Personal sound zone systems provide concurrent, interference-free listening experiences to multiple listeners using loudspeaker arrays. Nonlinear distortion in loudspeaker drivers can cause audible artefacts and the acoustic contrast can be degraded, especially at high driving levels. The distortion can be reduced by constraining the total control effort, but artefacts can still be present due to one or several loudspeaker drivers having high control effort. To reduce nonlinear distortion we applied individual control effort constrained acoustic contrast control (ICECACC), where control effort constraints are imposed for each individual loud- speaker driver. Simulations and experiments were performed on a two sound-zone setup with one bright and one dark zone using ICECACC or acoustic contrast control (ACC) and a two-tone stimulus generating both harmonic and intermodulation distortion. Frequency resolved measurements show that ICECACC and ACC give nearly identical acoustic contrast at the two fundamental frequencies, but ICECACC has less nonlinear distortion than ACC. Experiments using a multi-tone stimulus and identical total control efforts also gave reduced nonlinear distortion with ICECACC over ACC, however this was achieved at the expense of contrast. The results show that a compromise can be made between acoustic contrast and nonlinear distortion.

AB - Personal sound zone systems provide concurrent, interference-free listening experiences to multiple listeners using loudspeaker arrays. Nonlinear distortion in loudspeaker drivers can cause audible artefacts and the acoustic contrast can be degraded, especially at high driving levels. The distortion can be reduced by constraining the total control effort, but artefacts can still be present due to one or several loudspeaker drivers having high control effort. To reduce nonlinear distortion we applied individual control effort constrained acoustic contrast control (ICECACC), where control effort constraints are imposed for each individual loud- speaker driver. Simulations and experiments were performed on a two sound-zone setup with one bright and one dark zone using ICECACC or acoustic contrast control (ACC) and a two-tone stimulus generating both harmonic and intermodulation distortion. Frequency resolved measurements show that ICECACC and ACC give nearly identical acoustic contrast at the two fundamental frequencies, but ICECACC has less nonlinear distortion than ACC. Experiments using a multi-tone stimulus and identical total control efforts also gave reduced nonlinear distortion with ICECACC over ACC, however this was achieved at the expense of contrast. The results show that a compromise can be made between acoustic contrast and nonlinear distortion.

UR - http://www.scopus.com/inward/record.url?scp=85072973195&partnerID=8YFLogxK

U2 - 10.17743/jaes.2019.0015

DO - 10.17743/jaes.2019.0015

M3 - Journal article

SN - 1549-4950

VL - 67

SP - 641

EP - 654

JO - Journal of the Audio Engineering Society

JF - Journal of the Audio Engineering Society

IS - 9

ER -