Yup I have seen bungs supplied with the speaker by the manufacturer. Cork, Rubber.
Cotton Wool or Polyester are quite interesting because they can be tweaked by compressing them.


Perhaps the issue of where sound is coming from, the suggestion that MEs should print speaker management into the audio, and the directional nature of one of the most common LF instruments, are all pertinent to topic after all.
I have seen speaker manufacturers recommend multiple full range sources rather than LF management for 5.1 rigs.

I believe quite a lot of reality is self evident. The initial wave front of a Kick Drum has trajectory. It has a starting point and will travel to say a candle flame, blowing it out. If the wavefront shown below comes at you from a full range say Left speaker, it will be very obviously sourced. Very differently to blasting equally from both sides as Mono LF would impose. A balanced cyclical wave could not do this. This 'blast' can be felt, which is how we hear such singularities, and for that matter ELF. It can be seen in the cone movement. It can be seen in the recording below. The first cycle is louder, asymmetric, and a different frequency to the subsequent settled tone.
In context the first two very unbalanced half cycles do not qualify for treatment as 50Hz. The actual pitch happens later.
http://www.soundonsound.com/sound-ad...-we-hear-pitch



DD