Hypothesis: Music Is A Super-Stimulus For The Perception Of Slow Speech Tempo

20 March, 2024
The neuronal system of speech tempo perception correctly perceives the tempo of both speech and music
But, according to the hypothesis being presented here, there also exists a separate glial system of speech tempo perception.
The glial system correctly perceives the tempo of normal speech, in the absence of music.
But, when music is present, the specific contrived features of music confound the glial system of tempo perception, resulting in a false perception of a very slow tempo, which in turn results in neuronal dysregulation, which is what is responsible for the emotional effects of listening to music.

The Perception of Speech Tempo

This article presents a hypothesis about the perception of speech tempo.

But it is not a hypothesis about the conscious perception of speech tempo.

It is a hypothesis about the glial perception of speech tempo.

What is glial perception?

In our brains, neurons are the brain cells that do the thinking, and glial cells are the cells that support the neurons, helping them, in various ways, to do their thinking.

Neurons are the cells that do most of the information processing in the brain.

But glial cells do have to do some information processing of their own. In order to interact with neurons, the glial cells have to observe various aspects of the state and activity of the neurons that they are supporting, so that they can interact correctly and usefully with the neurons.

These observations of neural state and activity are a form of perception, and that is how we arrive at the concept of "glial perception".

So, why do glial cells need to perceive speech tempo, and how do they perceive speech tempo, and why do they need to have their own separate system of tempo perception (ie separate from the neural perception of tempo perception that underlies our conscious perception of tempo), and what is it about music that confuses this glial tempo perception system?

The following is a basic outline of the why and the how and the what:

A Numerical Example

(Added 11 Apr, 2024)

To clarify the distinction between neuronal perception of speech tempo and glial perception of speech tempo, I will give a simple example with numbers that nominally represent those perceptions.

Firstly, let us suppose that a person is speaking at 120bpm.

Then we would expect that:

Now suppose that that person speeds up and speaks at 150bpm.

The perceptions would then be:

In these cases the neuronal perception and glial perception are both correct. The neuronal perception corresponds to the listener's conscious perception of tempo. The listener is not consciously aware of the glial perception, but when the glial perception of tempo increases by 25%, this coordinates an adjustment to the operating characteristics of all the neurons processing information downstream of the perceived vocal audio to match the increased speed at which the audio information is being received by the listener's brain.

Next, let suppose that powerful music is being performed at 120bpm.

In this case we find a difference, but only in the glial perception. That is:

The neuronal perception remains correct, but the glial perception now underestimates the tempo by a factor of 5.

This underestimation then causes an intensifications of emotional response by a factor that is a function of the tempo underestimation factor.

It might for example be the same factor, ie the function is the identity function and the emotion is intensified by a factor of 5. (It could be some other function, for example a different power law. However there is at the moment no way to directly measure either of these factors, so to keep it simple, for the sake of clarification, I will assume a simple identity function.)

What happens if the music is now performed at 150bpm?

If it's the same music, and the change in tempo does not adversely affect the musical strength, then the underestimation factor will be similar, ie:

And the emotional intensifaction factor will be the same, ie 5.