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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: 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.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.

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.


Related in: MedlinePlus

(a) Top view of the measurement system setup showing how the azimuth angle is defined, and (b) side view of the measurement system setup showing how the elevation angle is defined. (Not to scale)
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f1-jres.118.005: (a) Top view of the measurement system setup showing how the azimuth angle is defined, and (b) side view of the measurement system setup showing how the elevation angle is defined. (Not to scale)

Mentions: Figure 1a shows the top view and Fig. 1b shows the side view of the measurement system setup and how the azimuth and elevation angles are defined between the reference axis of the manikin, which is mounted vertically in a position corresponding to that of a standing person, and the test axis of the sound source. The reference axis originates at the midpoint of the line joining the centers of the ear canal openings, known as the reference point of the manikin, and is normal to the vertical plane that contains this line. The test axis originates at the test point, which is the point in the test space where the reference point of the manikin is located during testing. This axis joins the test point and the center of the sound source. When the reference point of the manikin coincides with the test point, and the test axis coincides with the reference axis of the manikin (α = 0° and θ = 0°), the manikin is in the reference position and the sound source is located at what will be referred to here as the reference axis location. All sound source locations have a distance of 1.00 m ± 0.05 m from the test point.


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

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

(a) Top view of the measurement system setup showing how the azimuth angle is defined, and (b) side view of the measurement system setup showing how the elevation angle is defined. (Not to scale)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1-jres.118.005: (a) Top view of the measurement system setup showing how the azimuth angle is defined, and (b) side view of the measurement system setup showing how the elevation angle is defined. (Not to scale)
Mentions: Figure 1a shows the top view and Fig. 1b shows the side view of the measurement system setup and how the azimuth and elevation angles are defined between the reference axis of the manikin, which is mounted vertically in a position corresponding to that of a standing person, and the test axis of the sound source. The reference axis originates at the midpoint of the line joining the centers of the ear canal openings, known as the reference point of the manikin, and is normal to the vertical plane that contains this line. The test axis originates at the test point, which is the point in the test space where the reference point of the manikin is located during testing. This axis joins the test point and the center of the sound source. When the reference point of the manikin coincides with the test point, and the test axis coincides with the reference axis of the manikin (α = 0° and θ = 0°), the manikin is in the reference position and the sound source is located at what will be referred to here as the reference axis location. All sound source locations have a distance of 1.00 m ± 0.05 m from the test point.

Bottom Line: 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.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.

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.


Related in: MedlinePlus