Subject: Re: Physics of the sound of footsteps From: Mark Riggle <markriggle@xxxxxxxx> Date: Wed, 22 Jan 2014 10:20:03 -0500 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>--089e0158b242bd0bcd04f090a8e2 Content-Type: text/plain; charset=ISO-8859-1 How interesting you would be interested in the footstep. The human walk is unique in producing that particular sound heard internally via the skeleton. Our footstep has the foot hitting the floor with only a vertical velocity (the horizontal is at or nearly zero). The foot-bones stop so rapidly that the force on them causes a compression wave to start there. That wave travels up the skeleton to the skull -- that causes a high G (>1g) jerk on the head. That is what is heard and vestibularly felt -- that shockwave is passing through the skull. This is only in the human walk. In human adults it is referred to as the heel strike transient. However, the earlier developmental walks (infant and young child), although mechanically different, will also produce that audible shockwave. So search for heel strike transient. The audible effect however seems ignored - only the high skeletal jerk is investigated. What is interesting to me is this is the same pattern that occurs with very loud rock-music. The walk produces about 120 bpm of a vestibular jolt (that could produce a VEMP response) that is also audible, and when rock-music is louder than about 95 dB, it does the same. That is not a coincidence that these are only in humans. There are some other human unique behaviors supporting that claim. If you do a study on the acoustic part of that shockwave, please let me know. On Tue, Jan 21, 2014 at 11:45 AM, Linda Seltzer <lseltzer@xxxxxxxx > wrote: > When we walk, we can hear our footsteps, even if we are walking barefoot > on a soft surface. However, the number of steps per second in walking is > below the auditory range. What is it about the impact with the ground > that causes the auditory signal? Are there papers on the acoustics of a > footstep? > > Thank you for any information. > > Linda Seltzer > --089e0158b242bd0bcd04f090a8e2 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div><div>How interesting you would be interested in the f= ootstep.=A0 The=20 human walk is unique in producing that particular sound heard internally via the skeleton.=A0 Our footstep has the foot hitting the floor with=20 only a vertical velocity (the horizontal is at or nearly zero).=A0 The=20 foot-bones stop so rapidly that the force on them causes a compression=20 wave to start there.=A0 That wave travels up the skeleton to the skull --= =20 that causes a high G (>1g) jerk on the head. =A0 That is what is heard= =20 and vestibularly=A0 felt -- that shockwave is passing through the skull.=A0= =A0 This=A0 is only in the human walk.=A0 In human adults it is referred to as= =20 the heel strike transient.</div> However, the earlier developmental walks (infant and young child),=20 although mechanically different,=A0 will also produce that audible=20 shockwave.<br></div>So search for heel strike transient.=A0=A0 The audible = effect however seems ignored - only the high skeletal jerk is investigated.= <br> <div><br></div><div>What is interesting to me is this is the same=20 pattern that occurs with very loud rock-music.=A0 The walk produces about= =20 120 bpm of a vestibular jolt (that could produce a VEMP response) that=20 is also audible, and when rock-music is louder than about 95 dB, it does the same. <br> </div><div>That is not a coincidence that these are only in humans.=A0 Ther= e are some other human unique behaviors supporting that claim.<br><br></div= >If you do a study on the acoustic part of that shockwave, please let me kn= ow.<div class=3D""> <div id=3D":2l4" class=3D"" tabindex=3D"0"><img class=3D"" src=3D"https://m= ail.google.com/mail/images/cleardot.gif"></div></div></div><div class=3D"gm= ail_extra"><br><br><div class=3D"gmail_quote">On Tue, Jan 21, 2014 at 11:45= AM, Linda Seltzer <span dir=3D"ltr"><<a href=3D"mailto:lseltzer@xxxxxxxx= caltech.edu" target=3D"_blank">lseltzer@xxxxxxxx</a>></span> w= rote:<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex">When we walk, we can hear our footsteps, eve= n if we are walking barefoot<br> on a soft surface. =A0However, the number of steps per second in walking is= <br> below the auditory range. =A0What is it about the impact with the ground<br= > that causes the auditory signal? =A0Are there papers on the acoustics of a<= br> footstep?<br> <br> Thank you for any information.<br> <span class=3D"HOEnZb"><font color=3D"#888888"><br> Linda Seltzer<br> </font></span></blockquote></div><br></div> --089e0158b242bd0bcd04f090a8e2--