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NIST System for Measuring the Directivity Index of Hearing Aids under Simulated Real-Ear Conditions.

Wagner RP - J Res Natl Inst Stand Technol (2013)

Bottom Line: Since this response is different for a hearing aid worn on a person as compared to when it is in a free field, directivity index measurements of hearing aids are usually done under simulated real-ear conditions.Omnidirectional, cardioid, and bidirectional response patterns were measured.Results are presented comparing the NIST data with the reference values calculated from the data reported by all participating laboratories.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8223.

ABSTRACT
The directivity index is a parameter that is commonly used to characterize the performance of directional hearing aids, and is determined from the measured directional response. Since this response is different for a hearing aid worn on a person as compared to when it is in a free field, directivity index measurements of hearing aids are usually done under simulated real-ear conditions. Details are provided regarding the NIST system for measuring the hearing aid directivity index under these conditions and how this system is used to implement a standardized procedure for performing such measurements. This procedure involves a sampling method that utilizes sound source locations distributed in a semi-aligned zone array on an imaginary spherical surface surrounding a standardized acoustical test manikin. The capabilities of the system were demonstrated over the frequency range of one-third-octave bands with center frequencies from 200 Hz to 8000 Hz through NIST participation in an interlaboratory comparison. This comparison was conducted between eight different laboratories of members of Working Group S3/WG48, Hearing Aids, established by Accredited Standards Committee S3, Bioacoustics, which is administered by the Acoustical Society of America and accredited by the American National Standards Institute. Directivity measurements were made for a total of six programmed memories in two different hearing aids and for the unaided manikin with the manikin right pinna accompanying the aids. Omnidirectional, cardioid, and bidirectional response patterns were measured. Results are presented comparing the NIST data with the reference values calculated from the data reported by all participating laboratories.

No MeSH data available.


Polar response patterns measured at NIST in the horizontal plane at α = 0° for the one-third-octave band with a center frequency of 500 Hz. Measured data are shown only for azimuth angles included in the forty eight point semi-aligned zone array, the lines in between these angles were interpolated. Response data are displayed for (a) a hearing aid programmed with a cardioid pattern, (b) a hearing aid programmed with a bidirectional pattern, (c) a hearing aid programmed with an omnidirectional pattern (d) an unaided manikin.
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f4-jres.118.005: Polar response patterns measured at NIST in the horizontal plane at α = 0° for the one-third-octave band with a center frequency of 500 Hz. Measured data are shown only for azimuth angles included in the forty eight point semi-aligned zone array, the lines in between these angles were interpolated. Response data are displayed for (a) a hearing aid programmed with a cardioid pattern, (b) a hearing aid programmed with a bidirectional pattern, (c) a hearing aid programmed with an omnidirectional pattern (d) an unaided manikin.

Mentions: To show examples of the directional response patterns programmed in the aids used in the inter-laboratory comparison and intrinsic to the unaided manikin, polar response patterns measured at NIST in the horizontal plane at α = 0° for three of the programmed memories and the unaided manikin are displayed in Fig. 4a through Fig. 4d. All these patterns were obtained for the one-third-octave band with a center frequency of 500 Hz. The figures display measured data only for azimuth angles included in the forty-eight point semi-aligned zone array. The lines in between these angles were interpolated. As expected, due to the simulated real-ear measurement conditions, all these response patterns appear asymmetric.


NIST System for Measuring the Directivity Index of Hearing Aids under Simulated Real-Ear Conditions.

Wagner RP - J Res Natl Inst Stand Technol (2013)

Polar response patterns measured at NIST in the horizontal plane at α = 0° for the one-third-octave band with a center frequency of 500 Hz. Measured data are shown only for azimuth angles included in the forty eight point semi-aligned zone array, the lines in between these angles were interpolated. Response data are displayed for (a) a hearing aid programmed with a cardioid pattern, (b) a hearing aid programmed with a bidirectional pattern, (c) a hearing aid programmed with an omnidirectional pattern (d) an unaided manikin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487306&req=5

f4-jres.118.005: Polar response patterns measured at NIST in the horizontal plane at α = 0° for the one-third-octave band with a center frequency of 500 Hz. Measured data are shown only for azimuth angles included in the forty eight point semi-aligned zone array, the lines in between these angles were interpolated. Response data are displayed for (a) a hearing aid programmed with a cardioid pattern, (b) a hearing aid programmed with a bidirectional pattern, (c) a hearing aid programmed with an omnidirectional pattern (d) an unaided manikin.
Mentions: To show examples of the directional response patterns programmed in the aids used in the inter-laboratory comparison and intrinsic to the unaided manikin, polar response patterns measured at NIST in the horizontal plane at α = 0° for three of the programmed memories and the unaided manikin are displayed in Fig. 4a through Fig. 4d. All these patterns were obtained for the one-third-octave band with a center frequency of 500 Hz. The figures display measured data only for azimuth angles included in the forty-eight point semi-aligned zone array. The lines in between these angles were interpolated. As expected, due to the simulated real-ear measurement conditions, all these response patterns appear asymmetric.

Bottom Line: Since this response is different for a hearing aid worn on a person as compared to when it is in a free field, directivity index measurements of hearing aids are usually done under simulated real-ear conditions.Omnidirectional, cardioid, and bidirectional response patterns were measured.Results are presented comparing the NIST data with the reference values calculated from the data reported by all participating laboratories.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8223.

ABSTRACT
The directivity index is a parameter that is commonly used to characterize the performance of directional hearing aids, and is determined from the measured directional response. Since this response is different for a hearing aid worn on a person as compared to when it is in a free field, directivity index measurements of hearing aids are usually done under simulated real-ear conditions. Details are provided regarding the NIST system for measuring the hearing aid directivity index under these conditions and how this system is used to implement a standardized procedure for performing such measurements. This procedure involves a sampling method that utilizes sound source locations distributed in a semi-aligned zone array on an imaginary spherical surface surrounding a standardized acoustical test manikin. The capabilities of the system were demonstrated over the frequency range of one-third-octave bands with center frequencies from 200 Hz to 8000 Hz through NIST participation in an interlaboratory comparison. This comparison was conducted between eight different laboratories of members of Working Group S3/WG48, Hearing Aids, established by Accredited Standards Committee S3, Bioacoustics, which is administered by the Acoustical Society of America and accredited by the American National Standards Institute. Directivity measurements were made for a total of six programmed memories in two different hearing aids and for the unaided manikin with the manikin right pinna accompanying the aids. Omnidirectional, cardioid, and bidirectional response patterns were measured. Results are presented comparing the NIST data with the reference values calculated from the data reported by all participating laboratories.

No MeSH data available.