Directivity of different hearing aid microphone locations

Area of Science:

• Audiology
• Acoustics
• Hearing Aid Technology

Background:

• Conventional Directivity Index (DI) is limited for hearing aids as it often excludes non-frontal sound sources.
• Assessing hearing aid performance in real-world listening scenarios requires a more comprehensive directivity measure.

Purpose of the Study:

• To introduce a novel single-number metric, the Overall Directivity Index (ODI), for quantifying hearing aid directivity.
• To compare the directivity of various hearing aid styles against an open ear condition.

Main Methods:

• Developed the Overall Directivity Index (ODI) as an extension of the conventional Directivity Index (DI).
• Evaluated the directivity of five distinct hearing aid styles, including behind-the-ear (BTE) models, and compared them to an open ear.
• Applied an articulation index weighting and a 0-30 degree listening segment for ODI calculation.

Main Results:

• Behind-the-ear (BTE) hearing aids exhibited the lowest directionality among the tested styles and the open ear.
• Minimal directivity differences were observed among the four in-ear hearing aid styles and the open ear canal.
• The ODI metric provides a more realistic assessment of hearing aid directionality in everyday listening situations.

Conclusions:

• The proposed Overall Directivity Index (ODI) is a more suitable measure for assessing hearing aid directivity in real-world conditions.
• Behind-the-ear (BTE) hearing aids may offer less directional benefit compared to other styles.
• The ODI metric, incorporating articulation index weighting, enhances the evaluation of hearing aid performance.