Frequency-Modulation Distortion in Loudspeakers

Beers, G.; Belar, Herbert

doi:10.1109/jrproc.1943.229730

Cited by 10 publications

(4 citation statements)

References 1 publication

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“…It is clear from these observations that the particle velocity v at any space-time coordinates ðZ; t a Þ 2 K a n can be computed from (7), if the departure time t d is known. However, equation (8) shows that the existence of t d is conditionned by the existence of K À1 n , the reciprocal of K n .…”

Section: Methods Of Characteristicsmentioning

confidence: 99%

“…Initial investigations were carried out by Beers and Belar [7], who measured sound distortion generated by a two-tone vibrating diaphragm and derived a criterion for the evaluation of the Doppler distortion magnitude. Various models have been proposed to describe this phenomenon: (i) van Wulfften Palthe [1] adopted a pulsating sphere as a loudspeaker radiation approximation and performed calculation of intermodulation distortion, considering both the moving-boundary effect (Doppler) and the nonlinear propagation; (ii) Braun [8] established a time-domain formulation of the problem, followed by Butterweck [9] who derived a series solution for plane waves propagation generated by a vibrating piston in an infinite baffle; (iii) Zóltogórski [10] added nonlinear propagation effects to Butterweck's model, and presented a preliminary design of an anti-Doppler filter.…”

Section: Introductionmentioning

confidence: 99%

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Correction of the Doppler distortion generated by a vibrating baffled piston

Lebrun

Hélie

2020

Acta Acust.

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The Doppler effect is a phenomenon inherent to source motion, which introduces a variable propagation time between the source and a listening point. In the case of a vibrating piston, this is responsible for distortion of the radiated sound pressure. This moving-boundary phenomenon is part of the nonlinear effects involved in loudspeaker radiation. The present paper investigates the significance of this distortion, usually considered as neglectible, and addresses its correction. First, the direct problem is solved by: (a) converting the (Lagrangian) position of the moving source into its equivalent (Eulerian) velocity field at a fixed position; (b) deriving the acoustic pressure radiated from this velocity field. A series solution of (a) is derived and timedomain simulations of (b) are built from the truncated series combined with a baffled piston radiation model. Simulations show that Doppler distortion can be significant for realistic loudspeaker diaphragm motion with a wide spectral content. Second, the inverse (anti-Doppler) problem is examined, that is, the derivation of a piston displacement that generates a targeted Eulerian velocity field. The corrected piston velocity solution proves to be an uncentered signal, leading to a diverging displacement. In order to remove this practical problem, a centered approximation is preferred, based on modified inverse Volterra kernels. The anti-Doppler algorithm is reliable in the audio range.

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Section: Methods Of Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Correction of the Doppler distortion generated by a vibrating baffled piston

Lebrun

Hélie

2020

Acta Acust.

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“…The principal midband rollo commence at what is called the mass break point, fHM, given by: {an = (my/EREMMS (5) where MM; is the mass of the moving system. For most HF compression drivers the mass breakpoint takes place around 2500 to 4500 Hz.…”

Section: Early Developmentmentioning

confidence: 99%

Direct Radiators Versus Horn Loading: Design Principles and Historical Perspective in Sound Reinforcement

GANDER,

EARGLE

2024

Reproduced Sound 1996

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“…An early appreciation of the importance of minimizing distortion in such a system was obtained in development work on high-fidelity radio receivers. During the development of this receiver, consideration was given to the part which the loudspeaker might contribute to the over-all distortion in a sound-reproducing system [2]. Distortion is anything that alters a pure input signal in any way other than changing its magnitude.…”

Section: Introductionmentioning

confidence: 99%

Loudspeaker fault detection using Artificial Neural Network

Paulraj

Yaacob

Saad

2008

2008 International Conference on Electronic Design

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Traditionally, loudspeaker's quality control has been done manually and inspection of loudspeaker faults is time consuming and causes error in the quality evaluation. In order to reduce the time consumption and errors in the quality evaluation, in this research work, a simple loudspeaker diagnosing system is developed based on the harmonic distortion. The faulty and normal loudspeakers are tested using the sound emanated from the loudspeaker in the frequency range between 20 Hz and 20,000 Hz. A Fast Fourier Transform (FFT) is applied on the recorded signal to transform from time domain to frequency domain and the frequency spectrum is obtained. From the frequency spectrum, first six frequency band and it corresponds the total energy are computed and chosen for further analysis. The total energy of the each frequency band signal are obtained and used as features for training the neural network. A simple neural network model is developed for the automatic detection of loudspeaker faults. From the result it is observed that the proposed method is able to classify the faults with an accuracy level of 84%.

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Frequency-Modulation Distortion in Loudspeakers

Cited by 10 publications

References 1 publication

Correction of the Doppler distortion generated by a vibrating baffled piston

Correction of the Doppler distortion generated by a vibrating baffled piston

Direct Radiators Versus Horn Loading: Design Principles and Historical Perspective in Sound Reinforcement

Loudspeaker fault detection using Artificial Neural Network

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