Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer Modeling

Micro-Electro-Mechanical Systems (MEMS) loudspeakers are attracting growing interest as alternatives to conventional miniature transducers for in-ear audio applications. However, their practical deployment is often hindered by pronounced resonances in their frequency response, caused by the mechanic...

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Main Authors: Oliviero Massi, Riccardo Giampiccolo, Alberto Bernardini
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Micromachines
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Online Access:https://www.mdpi.com/2072-666X/16/6/655
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author Oliviero Massi
Riccardo Giampiccolo
Alberto Bernardini
author_facet Oliviero Massi
Riccardo Giampiccolo
Alberto Bernardini
author_sort Oliviero Massi
collection DOAJ
description Micro-Electro-Mechanical Systems (MEMS) loudspeakers are attracting growing interest as alternatives to conventional miniature transducers for in-ear audio applications. However, their practical deployment is often hindered by pronounced resonances in their frequency response, caused by the mechanical and acoustic characteristics of the device structure. To mitigate these limitations, we present a model-based digital signal equalization approach that leverages a circuit equivalent model of the considered MEMS loudspeaker. The method relies on constructing an inverse circuital model based on the nullor, which is implemented in the discrete-time domain using Wave Digital Filters (WDFs). This inverse system is employed to pre-process the input voltage signal, effectively compensating for the transducer frequency response. The experimental results demonstrate that the proposed method significantly flattens the Sound Pressure Level (SPL) over the 100 Hz-10 kHz frequency range, with a maximum deviation from the target flat frequency response of below 5 dB.
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institution DOAJ
issn 2072-666X
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publishDate 2025-05-01
publisher MDPI AG
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series Micromachines
spelling doaj-art-3dfe2c8e729a4e72bdff467309b425552025-08-20T03:16:23ZengMDPI AGMicromachines2072-666X2025-05-0116665510.3390/mi16060655Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer ModelingOliviero Massi0Riccardo Giampiccolo1Alberto Bernardini2Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano, ItalyDipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano, ItalyDipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano, ItalyMicro-Electro-Mechanical Systems (MEMS) loudspeakers are attracting growing interest as alternatives to conventional miniature transducers for in-ear audio applications. However, their practical deployment is often hindered by pronounced resonances in their frequency response, caused by the mechanical and acoustic characteristics of the device structure. To mitigate these limitations, we present a model-based digital signal equalization approach that leverages a circuit equivalent model of the considered MEMS loudspeaker. The method relies on constructing an inverse circuital model based on the nullor, which is implemented in the discrete-time domain using Wave Digital Filters (WDFs). This inverse system is employed to pre-process the input voltage signal, effectively compensating for the transducer frequency response. The experimental results demonstrate that the proposed method significantly flattens the Sound Pressure Level (SPL) over the 100 Hz-10 kHz frequency range, with a maximum deviation from the target flat frequency response of below 5 dB.https://www.mdpi.com/2072-666X/16/6/655MEMS loudspeakerspiezoelectric transducersequalizationinverse systems
spellingShingle Oliviero Massi
Riccardo Giampiccolo
Alberto Bernardini
Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer Modeling
Micromachines
MEMS loudspeakers
piezoelectric transducers
equalization
inverse systems
title Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer Modeling
title_full Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer Modeling
title_fullStr Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer Modeling
title_full_unstemmed Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer Modeling
title_short Equalizing the In-Ear Acoustic Response of Piezoelectric MEMS Loudspeakers Through Inverse Transducer Modeling
title_sort equalizing the in ear acoustic response of piezoelectric mems loudspeakers through inverse transducer modeling
topic MEMS loudspeakers
piezoelectric transducers
equalization
inverse systems
url https://www.mdpi.com/2072-666X/16/6/655
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AT riccardogiampiccolo equalizingtheinearacousticresponseofpiezoelectricmemsloudspeakersthroughinversetransducermodeling
AT albertobernardini equalizingtheinearacousticresponseofpiezoelectricmemsloudspeakersthroughinversetransducermodeling