Is this a musical effect with a name?

Cafe Society
1

I have a sketch of a few bars of music where, accidentally but to my ear pleasingly, while the music actually increases in tempo, the effect is of a slowing down.

This is due to the melody consisting, after the change, mostly in quarter notes instead of mostly in eighth notes (though the phrases are still the same length in terms of number of measures). I think that’s what’s creating the effect, though I’m not sure. The lower notes (kind of a base line) are quarters throughout, so they just increase in tempo.

I feel like I’ve heard this effect in some singers I’d characterize as having a more “theatrical” style. Amanda Palmer is the first person that came to mind, though no specific song came to mind.

Is this an effect with a name? Or is it just a thing I did that’s not particularly a technique, just a rhythm change?

Here’s the sketch of a few bars mentioned above:

2

It might be considered counterpoint. Counterpoint can be harmonic or rhythmic.

3

I’m not hearing this effect. It starts at ♩=160 and when the tempo changes to ♩=180, it’s indeed faster rather than supposedly slower.

4

Commonly, that section might come with a time signature change to cut time, further emphasizing the fact that the section really has a feel of 2 beats per measure. Or, just a notation above where the tempo change happens that says “Half-time feel” or something like that.