Re: [Sursound] Barber Poles and Zeroes (life in the S-domain?)
On 4/02/2013 8:51 PM, Dave Malham wrote: and scorpions hear vibrations through their feet and have incredibly good direction sensingI was particularly struck by your comment about distance perception, as that's one I hadn't thought about - I'll have to add that to my list I used to work with the astounding Scottish percussionist, Evelyn Glennie (who is profoundly deaf). She wears bare feet and combines lip-reading with vibrations through the ground/floor. American Indians (among others) can judge distances too by attenuation of frequencies. Haig ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Barber Poles and Zeroes (life in the S-domain?)
Hi Eric As always, an interesting and detailed post. I'll just comment on a couple of points... On 3 February 2013 20:29, Eric Carmichel wrote: > Aside from masking and audiometric protocols, the idea of sound transmitted > via bone conduction is important when it comes to normal-hearing listeners. > We probably don’t give it a lot of consideration to it because the > predominant ‘sensation’ is that of hearing, so we assume that sound only > reaches the inner ear via the outer ear. What we ‘feel’ at loud concerts is > identifiable as low-frequency vibration, but this certainly adds to the > ‘sound’ (I wonder whether we could induce motion sickness if the vibration > wasn’t in time with the airborne sound). Wouldn't surprise me at all! > Scientists have a good grasp on how we hear (meaning the physiological > aspects of the peripheral auditory system), but I fear we know little on how > we ‘listen’. Isolating simple sounds allows us to study and understand > important aspects of hearing, but humans (and other critters) as well as our > environments are complex. I’ll leave discussions of man-environment > interactions to Ecological Psychologists or their opponents. Dr. Lennox - comments? > Regarding dentally-implanted hearing aids, my scant knowledge of this is that > they are bone-conduction devices. Some children (and adults) may have > stenosis or atresia that precludes them from hearing despite a normal inner > ear system. This type of hearing loss is a conductive hearing loss. By > providing sound vibration to boney surfaces (such as the mandibular process), > the inner ear receives stimulation as though the footplate of the stapes were > acting on the oval window (middle and inner ear components). Sound travels > faster in a solid medium than it does for air, so the usual directional cues > are probably lost or would take time to ‘learn’ (the other aspect of > localization). > You can take a tuning fork and, while it’s vibrating, touch it to your > forehead, teeth, or prominent (hard) area just behind your ears. It is > evident from a simple demonstration that the increase in level is not merely > a result of sound reaching the outer ear. There’s a limit to high frequency > response via bone conduction because of inertia. It takes more energy to > accelerate a large mass. The light weight of the eardrum and bones of the > middle ear (ossicles) makes the middle ear an efficient moving system over a > broad range of frequencies. The limits are set by the sensory cells (inner > and outer hair cells) of the inner ear, not the mass or compliance of the > middle ear. Some years ago ( well, actually, over two decades) we were approached by Stanton Magnetics about their Mass Inertial Transducers which are (or were, they aren't available any longer as far as I can see, though similar devices are - see http://www.maplin.co.uk/10w-vibration-speaker-671562) vibrators based on US patent us4843628. We bought a couple and played around with them, ending up particularly interested in the way you could "hear" where they were placed on your body, even if the sound was at such at a low level that you couldn't hear them via the air or feel them as a an obviously tactile sensation. > Real-world hearing is multi-dimensional. I would be curious to know whether > our sense of distance is at all affected by the feeling sensation that > reaches us (via ground vibration) before airborne waves reach us. We are > conscious of the obvious, dominant cues that affect our perception of the > world. In the absence of the dominant cues, nature finds ways to fill gaps > and make sense of our environment. Pitch and melody may not be easily > recognizable when distorted, but rhythm is often identifiable. Speech, like > music, has rhythm and intonation (prosodic features). So ‘hearing’ with our > skin seems entirely plausible, particularly if we define hearing as an active > process of making sense of vibration. Reptiles are sensitive to infrasonic > frequencies: Maybe their hearing mechanism is akin to the utricle and > saccules that are responsible for our sense of balance. In fact, the organs > of balance reside in the inner ear, so why shouldn’t they also > contribute to our perception of sound (in addition to sound-source > direction). Just some thoughts, and me rambling on another Super Bowl Sunday. and scorpions hear vibrations through their feet and have incredibly good direction sensingI was particularly struck by your comment about distance perception, as that's one I hadn't thought about - I'll have to add that to my list All the best Dave As of 1st October 2012, I have retired from the University, so this disclaimer is redundant These are my own views and may or may not be shared by my employer Dave Malham Ex-Music Research Centre Department of Music The University of York Heslington York YO10 5DD UK 'Ambisonics - Component Imaging for Audio' ___
[Sursound] Barber Poles and Zeroes (life in the S-domain?)
Greetings everyone, I enjoyed the recent posts regarding binaural demos and headphones versus loudspeaker arrays. I am writing this post off the cuff, so I can’t site peer-reviewed articles immediately. But I believe what follows is accurate. Audiograms for individuals with profound hearing loss oftentimes suggest measurable, low-frequency hearing. Naturally, there is reason to question whether the sensation is, in fact, hearing or a vibrotactile response. It is easy to demonstrate our sensitivity to low-frequency vibration by lightly touching the cone of a loudspeaker. Not too many years back, the standard transducer for measuring hearing was the Telefonix earphone. Some profoundly deaf persons would indicate a ‘tickling’ sensation at the low (below 500 Hz) frequencies. Probably not a surprise when the presentation level was 90 dB HL (which equates to an even greater SPL at the low and high frequencies). Of greater concern to audiologist is that of unilateral or asymmetric hearing losses. Above a certain presentation level, bone conduction makes the sound clearly audible in the ‘better’ ear, which may not be the ear being tested. This ‘crosstalk’ is greatly minimized by use of insert phones (predominately EAR phones), but narrowband masking noise is used to ‘mask’ the test signal from the non-test ear. Of course, the masking noise itself could be audible in the opposite ear if the masking noise level (in HL or SPL) is greater than the inter-aural attenuation (dB) of bone and tissue. Aside from masking and audiometric protocols, the idea of sound transmitted via bone conduction is important when it comes to normal-hearing listeners. We probably don’t give it a lot of consideration to it because the predominant ‘sensation’ is that of hearing, so we assume that sound only reaches the inner ear via the outer ear. What we ‘feel’ at loud concerts is identifiable as low-frequency vibration, but this certainly adds to the ‘sound’ (I wonder whether we could induce motion sickness if the vibration wasn’t in time with the airborne sound). I don’t have knowledge of persons who can discern pitch through touch (skin), but any type of vibrotactile (or even visual) response that is rhythmic could be discerned as a pattern that can be associated with music or speech. For persons who were deaf at birth (congenital deafness; not necessarily genetic causes), there is certainly reason to believe they have developed heightened sensitivity to such vibration, and, in extraordinary persons, pitch could be also be discernible. By the way, percussionists definitely tune their instruments to match other instruments in the orchestra/group. RE profound hearing loss at birth: Whether the brain creates synapses to accommodate hearing via tactile input at a young age (i.e. when the brain is plastic enough to do amazing things) could be studied using EEG mapping or fMR. The sense of hearing is generally associated with the temporal lobe (and further reduced to specific areas, or gyri and sulci). I do not know if these areas would ‘light up’ in response to other sensory input (such as applying vibration to the feet) for those persons. Please be aware that the temporal lobe represents higher level cortical function (pattern recognition and language), not necessarily sound-source direction. The latter may occur at the mid-brain (inferior or superior colliculus). Scientists have a good grasp on how we hear (meaning the physiological aspects of the peripheral auditory system), but I fear we know little on how we ‘listen’. Isolating simple sounds allows us to study and understand important aspects of hearing, but humans (and other critters) as well as our environments are complex. I’ll leave discussions of man-environment interactions to Ecological Psychologists or their opponents. Regarding dentally-implanted hearing aids, my scant knowledge of this is that they are bone-conduction devices. Some children (and adults) may have stenosis or atresia that precludes them from hearing despite a normal inner ear system. This type of hearing loss is a conductive hearing loss. By providing sound vibration to boney surfaces (such as the mandibular process), the inner ear receives stimulation as though the footplate of the stapes were acting on the oval window (middle and inner ear components). Sound travels faster in a solid medium than it does for air, so the usual directional cues are probably lost or would take time to ‘learn’ (the other aspect of localization). You can take a tuning fork and, while it’s vibrating, touch it to your forehead, teeth, or prominent (hard) area just behind your ears. It is evident from a simple demonstration that the increase in level is not merely a result of sound reaching the outer ear. There’s a limit to high frequency response via bone conduction because of inertia. It takes more energy to accelerate a large mass. The light weight of the eardrum and bones of th
