Proceedings abstract

 

A Sensory-Motor Theory IV: Vestibular responses to music.

 N.P.McAngus Todd, F.W. Cody and J. Banks. Department of Psychology

and School of Biological Sciences, University of Manchester, Manchester,

M13 9PL.

1. Background

Since the question "Is hearing all cochlear?" was posed some seven decades past (Tait, 1932), there has amassed considerable evidence that the sacculus, an organ of hearing in fish (Popper et al, 1982), has retained some acoustic sensitivity throughout phylogeny (McCue and Guinan, 1995). In humans, myogenic vestibular evoked potentials (MVEP) may be obtained from motorneurones inervated by the vestibulo-spinal tract, particularly from the cervical region of the spinal cord (Ferber-Viart et al, 1999). MVEP has been studied principally as non-invasive clinical tool for evaluation of normal otolith vestibular function, since traditional nystagmographic methods only assess canal function. However, we have been interested in using MVEP as a window on what possible 'auditory' function acoustic sensitivity sacculus may have.

2. Aim

To describe a series of experiments designed to investigate the role of acoustic sensitivity of the sacculus in the perception of sounds.

(1) Effect of requency,

(2) threshold of response to dance music and

(3) effect of stimulus duration.

3. Method

MVEP was obtained in response to:

  1. 110 dB tone pips with frequencies ranging from 100 Hz to 3200 Hz;
  2. a cycle of techno music at a range of intensities from 90 - 120 dB SPL and
  3. 100 Hz click trains and tones bursts.

4. Results.

  1. MVEP has a frequency tuning (Todd, Cody and Banks, in press), with a best frequency between 300 Hz - 350 Hz and a band-width of about 3 octaves. This response is consistent with it being saccularly mediated, particularly since we were able to model the selectivity by means of a mass-spring-damper system with a Q of about 0.7.
  2. MVEP can be obtained to 'natural' acoustic stimuli (Todd and Cody, 2000), such as dance music, above about 90 dB SPL.
  3. MVEP can be obtained to continuous sounds (Todd, in preparation), i.e. a frequency-following response may be obtained with longer duration stimuli, suggesting that acoustically evoked phase-locking is taking place in the saccular nerve giving rise to the adaptation and inhibition characteristic of normal sensory transduction.

5. Conclusions

Given the above then, there are a number of natural stimuli, including vocal and musical sounds, where saccular acoustic sensitivity may play a role in perception. Such sensations could be vestibular or 'auditory' since there exists anatomical evidence of a saccular projection to the cochlear nucleus (Burian et al, 1989). Further, such a mechanism could interact with a more general sensory-motor mechanism (Todd, 1999) involved in rhythmic processing, particularly given the input that the vestibular system has to the cerebellum.

 

Burian, M., Gstoettner, W. and Zundritsch, R. Arch Otolaryngol, 1989; 246: 238-241.

Ferber-Viart. C., Ducleax, R., Colleaux, B. and Dubreuil, C. Acta Otolaryngol (Stockh.), 1997; 117: 472-481.

McCue, M. and Guinan, J. J Neurophysiol, 1995; 74(4): 1563-1572.

Popper, A. Platt, C. and Saidal, W. TINS, 1982; August: 276-80.

Tait, J. Ann Otol Rhinol Laryngol, 1932; 41: 681-704.

Todd, N.P.McAngus (1999) Motion in Music: A neurobiological perspective. Music Perception. 17(1).

Todd, N.P.McAngus and Cody, F.W. (2000).Vestibular responses to loud dance music: A physiological basis for the "rock and roll threshold"? J Acoust Soc Am. 104(1).

Todd, N.P.McAngus , Cody, F.W. and Banks, J. A saccular origin of frequency tuning in myogenic vestibular evoked potentials?: Implications for human responses to loud sounds. Hear Res. (in press).

 

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