The Head Shadow Phenomenon Affected by Sound Source: In Vitro Measurement

Abstract:

This study focuses on establishing an in-vitro sound filed measurement system in order to investigate the effect of sound source angle and frequency on the head shadow effect (HSE). The study used sound stimuli at frequencies of 125 Hz, 250 Hz, 500 Hz, 750 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, 5 kHz, 6 kHz, 7 kHz, 8 kHz, and with sound source positioning at angles of 0, 30, 45, 60 and 90 degrees. It evaluated the effect these frequencies and positioning combinations had on the HSE. When the sound source was positioned at 90 degrees to the ear, this study found that the HSE not only existed at the frequencies of 4 kHz to 6 kHz, but also the HSE could be happened at 3 kHz, 7 kHz and 8 kHz. In addition, a significant influence on HSE was also demonstrated when the sound stimulus was positioned at 45 degrees to the ear, with a frequency range between 3 kHz~8 kHz. As well as considering head and ear anatomy and the head shadow effect when selecting and fitting hearing aids, it is also necessary to consider adjustment to account for angular sound sources at different sound frequencies.

• Periodical: Applied Mechanics and Materials (Volumes 284-287)
• Pages: 1715-1720
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.284-287.1715
• Online since: January 2013
• Authors: Jen Fang Yu, Yen Sheng Chen
• Keywords: Binaural Hearing, Head Shadow Effect, Sound Measurement, Sound Source

References

[1] J. M. Festen and R. Plomp, Speech-reception threshold in noise with one and two hearing aids, J Acoust Soc Am., 79, 465-471, (1986).

DOI: 10.1121/1.393534

[2] J. R. Dubno, J. B. Ahlstrom and A. R. Horwitz, Binaural advantage for younger and older adults with normal hearing, J Speech Lang Hear Res., 51, 539-556, (2008).

DOI: 10.1044/1092-4388(2008/039)

[3] S. A. Gelfand, Loudness. Hearing: an introduction to psychological and physiological acoustics, 4th ed, New York, Marcel Dekker, pp.393-411, (2004).

[4] M. M. Van Wanrooij and A. J. Van Opstal, Contribution of head shadow and pinna cues to chronic monaural sound localization, J Neurosci., 24, 4163-4171, (2004).

DOI: 10.1523/jneurosci.0048-04.2004

[5] D. W. Grantham, T. A. Ricketts, D. H. Ashmead, R. F. Labadie and D. S. Haynes, Localization by postlingually deafened adults fitted with a single cochlear implant, Laryngoscope, 118, 145-151, (2008).

DOI: 10.1097/mlg.0b013e31815661f9

[6] J. C. Chan, D. J. Freed, A. J. Vermiglio and S. D. Soli, Evaluation of binaural functions in bilateral cochlear implant users, Int J Audiol., 47, 296-310, (2008).

DOI: 10.1080/14992020802075407

[7] E. A. Shaw, Transformation of sound pressure level from the free field to the eardrum in the horizontal plane, J Acoust Soc Am., 56, 1848-1861, (1974).

DOI: 10.1121/1.1903522

[8] P. Senn, M. Kompis, M. Vischer and R. Haeusler, Minimum audible angle, just noticeable interaural differences and speech intelligibility with bilateral cochlear implants using clinical speech processors, Audiol Neurootol., 10, 342-352, (2005).

DOI: 10.1159/000087351

[9] T. Y. Ching, E. van Wanrooy, M. Hill and P. Incerti, Performance in children with hearing aids or cochlear implants: bilateral stimulation and binaural hearing, Int J Audiol., 45 Suppl 1, 108-112, (2006).

DOI: 10.1080/14992020600783087

[10] M. M. Van Wanrooij and A. J. Van Opstal, Sound localization under perturbed binaural hearing, J Neurophysiol., 97, 715-726, (2007).

DOI: 10.1152/jn.00260.2006