PMID- 29195468
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20190529
IS  - 1520-8524 (Electronic)
IS  - 0001-4966 (Linking)
VI  - 142
IP  - 5
DP  - 2017 Nov
TI  - Incorporating evanescent modes and flow losses into reference impedances in
      acoustic Thevenin calibration.
PG  - 3013
LID - 10.1121/1.5010891 [doi]
AB  - This paper proposes an alternative approach to acoustic Thevenin calibration of
      an ear probe. An existing methodology derives the Thevenin-equivalent source
      parameters from the measured probe pressures in a number of short waveguides by
      solving an overdetermined system of equations. This existing methodology is
      affected by errors caused by evanescent modes when the waveguide model lengths
      are estimated. These errors introduce a parallel acoustic compliance into the
      source parameters. The proposed methodology takes into account evanescent modes
      and flow losses in the transition between the probe tube and waveguides during
      calibration. This is achieved by positioning the probe tube, without an ear tip, 
      flush with the input plane in waveguides of well-defined dimensions and utilizing
      the physical rather than estimated lengths to calculate the analytical waveguide 
      models. Terms that model evanescent modes and flow losses are added to the
      plane-wave impedance and adjusted to minimize the calibration error. It is shown 
      that this method can reduce the calibration error across a wide frequency range
      and remove the parallel compliance from the source parameters. This approach
      leads to an independence of the source parameters on the calibration waveguide
      radius, though subsequent impedance measurements are still affected by evanescent
      modes.
FAU - Norgaard, Kren Rahbek
AU  - Norgaard KR
AD  - Acoustic Technology, Department of Electrical Engineering, Technical University
      of Denmark, Orsteds Plads, Building 352, Kongens Lyngby, DK-2800, Denmark.
FAU - Fernandez-Grande, Efren
AU  - Fernandez-Grande E
AD  - Acoustic Technology, Department of Electrical Engineering, Technical University
      of Denmark, Orsteds Plads, Building 352, Kongens Lyngby, DK-2800, Denmark.
FAU - Laugesen, Soren
AU  - Laugesen S
AD  - Interacoustics Research Unit, Technical University of Denmark, Orsteds Plads,
      Building 352, Kongens Lyngby, DK-2800, Denmark.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Acoust Soc Am
JT  - The Journal of the Acoustical Society of America
JID - 7503051
EDAT- 2017/12/03 06:00
MHDA- 2017/12/03 06:01
CRDT- 2017/12/03 06:00
PHST- 2017/12/03 06:00 [entrez]
PHST- 2017/12/03 06:00 [pubmed]
PHST- 2017/12/03 06:01 [medline]
AID - 10.1121/1.5010891 [doi]
PST - ppublish
SO  - J Acoust Soc Am. 2017 Nov;142(5):3013. doi: 10.1121/1.5010891.