RC circuit at the output of the low frequency amplifier. What is it there for?

In low-frequency amplifier circuits, an RC circuit called the Bushe-Zobel circuit is installed in parallel with the speaker at the output. In the description, you can find that it is needed to ensure the same speaker resistance at different frequencies. It is also written that this circuit suppresses various signals from the amplifier output (interference), and these signals do not reach the speaker. I will check if this is true. The testing was carried out with a signal generator with a frequency of 20-20000 Hz and a low-frequency amplifier on the TDA2003 microcircuit. The resistor resistance is 1 Ohm, and the capacitor capacity is 0.1 μF

I first checked the effect of the chain on the speaker resistance and made sure that its resistance still changes at different frequencies and the chain does not particularly affect this.

Now I fed a signal from the generator to the amplifier input, connected the oscilloscope probes in parallel to the speaker and it is clear that the sine wave at a frequency of 1000 Hz is not distorted. This will be the case at the output of the power amplifier with an RC chain up to a frequency of 20,000 Hz

Now that I have removed the RC circuit, it is clear that the sine wave or signal coming out of the power amplifier is distorted, although the speaker sounds clean. The input of the power amplifier is 1 kHz, and the output is 30-100 kHz. This interference can cause distortion that will interfere with the operation of the amplifier

With a powerful low frequency amplifier, the resistor must also be powerful. It will generate heat, and this is the power of this interference