A Three Structure Model of Neural Activity in Relation to Consciousness and Language
In a previous post I suggested how speech might be accounted for by the three structure model. In retrospect I think there is some modification needed and I propose that speech has three components as per the diagram below.
Speech and the Three Structure Model
Unfortunately it has got a little complicated and the arrows cross each other in the diagram. Nevertheless this reflects the complexity of the interaction between mind and brain. I will explain the three divisions of speech in the three structure model.
With automatic speech, the neural activity takes place in the cranial nerves. At this stage all of the decisions about speech have been made and it has now became a matter of activating the muscle groups in a predetermined manner.
With sensory speech feedback, we become aware of the sound of our own voice as we are speaking as well as the other sensory feedback such as the movement of the jaw and the contact of the tongue with the palate. While it is more likely that this will impact on our consciousness it is also possible for it to act on us unconsciously. For example, if prose is well learnt and it is being repetitively rehearsed it may be possible to divert conscious activity to other matters.
Speech modifiers describes the decisions that are made about how we translate language into speech. Rather than simply speaking our ‘language script’ in a standardised manner, we are able to modify the tone, rate, rhythm and volume of speech. We do this in order to engage with the audience and also to communicate the emotional meaning of our speech. Again this can be conscious or unconscious.
The relationship is shown in the above diagram.
The description of speech in the three structure model can be better understood by considering the video below.
Vocalisation in a Video by Dr J.P.Thomas
In the above video, the singer is demonstrating
scales crescendo/decrescendo whilst stroboscopy reveals the corresponding changes in the larynx. The Larynx is a complex piece of anatomical apparatus featuring intrinsic and extrinsic muscles as well as vocal cords. The vocal cords vibrate up to 100 times per second.
As we view the clip the three components of speech are apparent after further reflection (although strictly speaking this is not speech it demonstrates the principles discussed above).
Firstly the automatic component of vocalisation is apparent. If we volitionally attempted to vibrate the vocal cords 100 times per second by focusing on the vocal cords themselves we would no doubt fail. Seeing the vocal cords might give us the opportunity for finer volitional control but it is unlikely given the rate at which they are vibrating with vocalisation. Additionally as we do not see our own vocal cords when we are speaking, our method of organising their movement must be entirely dependent on auditory feedback. We leave the finer details of achieving these movements to our cranial nerves and instead focus our conscious attention on the end result.
This brings us onto the second component of speech which is sensory feedback. The singer demonstrates a crescendo and decrescendo. Although this may be well rehearsed it is most likely that this technique requires close attention to the vocalisations produced up until that point. This feedback can be used to correct any deviation from the anticipated vocalisation.
Finally there is the crescendo and descrescendo. This is analogous to the speech modifiers which communicate the emotional content of our speech.
Speech remains outside of the three structure model. Nevertheless it is sufficiently complex to be usefully described in relation to the three structure model as it provides us with an intuitively understandable phenomenon that can be explained by this relatively abstract model.
Appendix – Related Resources on the TAWOP Site
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