Intelligibility of bone-conducted speech at different locations compared to air-conducted speech

Abstract

Bone-conduction transducers offer a unique advantage for radio communication systems, allowing sound transmission while the ear canals remain open for access to environmental sounds, or plugged for blocking of environmental sounds. This study compared the intelligibility of noise-degraded speech presented through bone-conduction hearing administered at different locations, and through air-conduction. Speech intelligibility was assessed using the Diagnostic Rhyme Test. Speech intelligibility was reduced for all of the bone-conduction hearing locations, relative to air-conduction hearing. There were also differences in performance for the various bone conduction locations. These results suggest that given noise-degraded speech, the performance decrement from using bone conduction will have to be weighed against the benefits of being able to dynamically block the ear canal, or leave it open, as situations require. Further, the choice of bone conduction transducer location would need to weigh possible performance differences against the various practical advantages of each location.

The effect of bone conduction microphone locations on speech intelligibility and sound quality

“…In the last few years, the United States Army Research Laboratory has conducted a series of research studies to determine basic properties of bone conduction communication (Letowski et al, 2004(Letowski et al, , 2005Henry and Letowski, 2007) and to identify effective head locations for bone conduction vibrators (McBride et al, 2005a(McBride et al, , b, 2008a. Several studies have also been conducted to determine which locations work best when transmitting speech signals (OsafoYeboah et al, 2009(OsafoYeboah et al, , 2006aSnidecor et al, 1959) and compare the intelligibility of speech transmitted via bone conduction vibrators to speech transmitted via air conduction earphones (Gripper et al, 2007;Osafo-Yeboah et al, 2006a, b;Stanley and Walker, 2009). In addition, there have been a few studies designed to demonstrate the feasibility of spatial listening using bone conducted signals (MacDonald et al, 2006;Walker and Lindsay, 2005;.…”

A free-field method to calibrate bone conduction transducers

“…Bone conduction involves sound transmission through the bone and soft tissue of the head, so the placement of bone conduction devices is likely to have strong influence on signal transmission (Snidecor et al, 1959;Acker-Mills et al, 2005;Stenfelt and Goode, 2005;Gripper et al, 2007;McBride et al, 2008a;McBride et al, 2008b;Osafo-Yeboah et al, 2009;Stanley and Walker, 2009;McBride et al, 2011). Two skull locations were investigated in this study: the mastoid process, which is a common transducer location for hearing aids and clinical applications and is also useful for communications (McBride et al, 2008a;McBride et al, 2008b;Osafo-Yeboah et al, 2009;McBride et al, 2011), and the mandibular condyle, which is a commonly used and effective location for bone conduction communication (McBride et al, 2008a;McBride et al, 2008b;OsafoYeboah et al, 2009;Stanley and Walker, 2009;McBride et al, 2011).…”

“…Two skull locations were investigated in this study: the mastoid process, which is a common transducer location for hearing aids and clinical applications and is also useful for communications (McBride et al, 2008a;McBride et al, 2008b;Osafo-Yeboah et al, 2009;McBride et al, 2011), and the mandibular condyle, which is a commonly used and effective location for bone conduction communication (McBride et al, 2008a;McBride et al, 2008b;OsafoYeboah et al, 2009;Stanley and Walker, 2009;McBride et al, 2011).…”

“…A variety of different skull locations may also be used. For example, the mandibular condyle has been shown to be an effective location for bone-conducted speech communication (Gripper et al, 2007;McBride et al, 2008b;Stanley and Walker, 2009), but it is not included in the calibration standards.…”

“…Bone conduction transducers can also be used without obstructing a listener's ears and without interfering with hearing protection devices. These benefits make bone conduction an attractive means for radio communication, and several laboratories have conducted investigations using a variety of bone conduction transducer devices placed at various skull locations (e.g., McBride et al, 2008a;McBride et al, 2008b;Osafo-Yeboah et al, 2009;Stanley and Walker, 2009;Tran and Letowski, 2010;McBride et al, 2011).…”