Near-field tangential particle velocities: Piston radiator vs. QRD phased linear array

Toby Gifford, Malcolm Duffield, Joe Hayes

    Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

    Abstract

    Loudspeakers in cars are constrained in size and placement. As such, near-field and mid-field sound properties are of interest. The near-field of a circular piston in an infinite baffle is well studied, and often used as an approximate model for a loudspeaker. Whilst a piston's SPL directivity pattern is well understood, its polar pattern of particle velocity direction has received less attention. We calculate the radial and tangential components of the piston model's particle velocity field, and find that tangential velocity dominates at particular angles for a given piston frequency. These polar positions relate to the 'dips' in the SPL directivity pattern. Contrasting these results with the sound-field of a linear array of spherical sound sources having phase delays determined by a QRD sequence, we find the QRD array yields greater uniformity in both SPL directivity and particle velocity direction.

    Original languageEnglish
    Title of host publicationAES 2017 International Conference on Automotive Audio
    Subtitle of host publication2017 AES International Conference on Automotive Audio
    Place of PublicationCA, United States
    PublisherAudio Engineering Society
    Pages1-8
    Number of pages8
    Volume2017-September
    Publication statusPublished - 29 Aug 2017
    EventAES 2017 International Conference on Automotive Audio - Burlingame, San Francisco, United States of America
    Duration: 8 Sep 201710 Sep 2017

    Conference

    ConferenceAES 2017 International Conference on Automotive Audio
    CountryUnited States of America
    CityBurlingame, San Francisco
    Period8/09/1710/09/17

    Keywords

    • acoustics
    • quadratic residue diffuser
    • particle velocity

    Cite this

    Gifford, T., Duffield, M., & Hayes, J. (2017). Near-field tangential particle velocities: Piston radiator vs. QRD phased linear array. In AES 2017 International Conference on Automotive Audio: 2017 AES International Conference on Automotive Audio (Vol. 2017-September, pp. 1-8). [P5-3] CA, United States : Audio Engineering Society.
    Gifford, Toby ; Duffield, Malcolm ; Hayes, Joe. / Near-field tangential particle velocities : Piston radiator vs. QRD phased linear array. AES 2017 International Conference on Automotive Audio: 2017 AES International Conference on Automotive Audio. Vol. 2017-September CA, United States : Audio Engineering Society, 2017. pp. 1-8
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    title = "Near-field tangential particle velocities: Piston radiator vs. QRD phased linear array",
    abstract = "Loudspeakers in cars are constrained in size and placement. As such, near-field and mid-field sound properties are of interest. The near-field of a circular piston in an infinite baffle is well studied, and often used as an approximate model for a loudspeaker. Whilst a piston's SPL directivity pattern is well understood, its polar pattern of particle velocity direction has received less attention. We calculate the radial and tangential components of the piston model's particle velocity field, and find that tangential velocity dominates at particular angles for a given piston frequency. These polar positions relate to the 'dips' in the SPL directivity pattern. Contrasting these results with the sound-field of a linear array of spherical sound sources having phase delays determined by a QRD sequence, we find the QRD array yields greater uniformity in both SPL directivity and particle velocity direction.",
    keywords = "acoustics, quadratic residue diffuser, particle velocity",
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    Gifford, T, Duffield, M & Hayes, J 2017, Near-field tangential particle velocities: Piston radiator vs. QRD phased linear array. in AES 2017 International Conference on Automotive Audio: 2017 AES International Conference on Automotive Audio. vol. 2017-September, P5-3, Audio Engineering Society, CA, United States , pp. 1-8, AES 2017 International Conference on Automotive Audio, Burlingame, San Francisco, United States of America, 8/09/17.

    Near-field tangential particle velocities : Piston radiator vs. QRD phased linear array. / Gifford, Toby; Duffield, Malcolm; Hayes, Joe.

    AES 2017 International Conference on Automotive Audio: 2017 AES International Conference on Automotive Audio. Vol. 2017-September CA, United States : Audio Engineering Society, 2017. p. 1-8 P5-3.

    Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

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    N2 - Loudspeakers in cars are constrained in size and placement. As such, near-field and mid-field sound properties are of interest. The near-field of a circular piston in an infinite baffle is well studied, and often used as an approximate model for a loudspeaker. Whilst a piston's SPL directivity pattern is well understood, its polar pattern of particle velocity direction has received less attention. We calculate the radial and tangential components of the piston model's particle velocity field, and find that tangential velocity dominates at particular angles for a given piston frequency. These polar positions relate to the 'dips' in the SPL directivity pattern. Contrasting these results with the sound-field of a linear array of spherical sound sources having phase delays determined by a QRD sequence, we find the QRD array yields greater uniformity in both SPL directivity and particle velocity direction.

    AB - Loudspeakers in cars are constrained in size and placement. As such, near-field and mid-field sound properties are of interest. The near-field of a circular piston in an infinite baffle is well studied, and often used as an approximate model for a loudspeaker. Whilst a piston's SPL directivity pattern is well understood, its polar pattern of particle velocity direction has received less attention. We calculate the radial and tangential components of the piston model's particle velocity field, and find that tangential velocity dominates at particular angles for a given piston frequency. These polar positions relate to the 'dips' in the SPL directivity pattern. Contrasting these results with the sound-field of a linear array of spherical sound sources having phase delays determined by a QRD sequence, we find the QRD array yields greater uniformity in both SPL directivity and particle velocity direction.

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    Gifford T, Duffield M, Hayes J. Near-field tangential particle velocities: Piston radiator vs. QRD phased linear array. In AES 2017 International Conference on Automotive Audio: 2017 AES International Conference on Automotive Audio. Vol. 2017-September. CA, United States : Audio Engineering Society. 2017. p. 1-8. P5-3