Reproducing Personal Sound Zones Using a Hybrid Synthesis of Dynamic and Parametric Loudspeakers

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Introduction

— Personalized audio environments in

spatialized zones

— Vehicle cabin entertainment/communication

systems

— Cinema surround sound systems

— Multi-participant teleconferencing

— Individual audio in restaurant/cafés

— Minimum sound leakage between zones

— High acoustic contrast

— Excellent speech quality

— Good speech privacy

Introduction

— Personalized audio environments in

spatialized zones

— Vehicle cabin entertainment/communication

systems

— Cinema surround sound systems

— Multi-participant teleconferencing

— Individual audio in restaurant/cafés

— Minimum sound leakage between zones

— High acoustic contrast

— Excellent speech quality

— Good speech privacy

Room

Multizone Soundfield Reproduction (MSR)(Dynamic Loudspeakers)

— Accurate multizone soundfield reproduction up

to spatial aliasing frequency

— Any arbitrary virtual source soundfield

— Large acoustic contrast between zones

— Spatial aliasing frequency can be solved

analytically

— Little to no multizone soundfield control above

aliasing frequency (proportional to number of

loudspeakers)

— Reduced acoustic contrast above aliasing frequency

Multizone Soundfield Reproduction (MSR)(Dynamic Loudspeakers)

Orthogonal basis expansion

Loudspeaker weights:

Multizone Soundfield Reproduction (MSR)(Dynamic Loudspeakers)

Orthogonal basis expansion

Loudspeaker weights:

Multizone Soundfield Reproduction (MSR)(Dynamic Loudspeakers)

Orthogonal basis expansion

Loudspeaker weights:

Parametric Loudspeaker (PL)

— Narrow directivity and large acoustic contrast at

high frequencies

— No spatial aliasing for wideband speech

(dependent on transducer spacing)

— Steerable beams with parametric loudspeaker

arrays

— Poor low frequency directivity and acoustic

contrast

— Sound pressure of the demodulated signal

limited to ~60dB

— greater harmonic distortion than dynamic

loudspeakers

Parametric Loudspeaker (PL)

Convolutional directivity

Parametric Loudspeaker (PL)

Convolutional directivity

Parametric Loudspeaker (PL)

Convolutional directivity

Parametric Loudspeaker (PL)

Convolutional directivity

Parametric Loudspeaker (PL)

Convolutional directivity

Hybrid Synthesis of Speech Soundfields

Multizone soundfield reproduction

— Large acoustic contrast

— Capable of high SPL

— Low harmonic distortion

Parametric Loudspeaker

— Large acoustic contrast

— Demodulated SPL suits speech levels

— Low harmonic distortion

— Wideband ~150Hz to 8kHz

— SPL ~60dB (decreasing at higher frequencies)

— Harmonic distortion reduces speech quality

Hybrid Synthesis of Speech Soundfields

— Analytically Derivable

— Zone dependent

— Distinguishes MSR high/low acoustic contrast boundary

— Minimum spectral distortion at crossover frequency

— Spatially dependent crossover frequency

(modal truncation length)

Hybrid Synthesis of Speech Soundfields

— Analytically Derivable

— Zone dependent

— Distinguishes MSR high/low acoustic contrast boundary

— Minimum spectral distortion at crossover frequency

— Spatially dependent crossover frequency

(modal truncation length)

smallest radius encompassing all zones

Hybrid Synthesis of Speech Soundfields

— Magnitude response of crossover filters sums to unity (no spectral distortion)

— Easily computed Butterworth polynomials

— Arbitrary crossover frequency

Hybrid Synthesis of Speech Soundfields

— Magnitude response of crossover filters sums to unity (no spectral distortion)

— Easily computed Butterworth polynomials

— Arbitrary crossover frequency

Hybrid Synthesis of Speech Soundfields

— Magnitude response of crossover filters sums to unity (no spectral distortion)

— Easily computed Butterworth polynomials

— Arbitrary crossover frequency

Hybrid Synthesis of Speech Soundfields

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Questions