10:40 pm EST
3:40 am GMT
1:08 pm EST
6:08 pm GMT
In most sound systems you just eliminate the 400hz band.
But not for the reason you think.
Speaker efficiency in that range detracts from the overall sound quality of the other 9 octaves.
It becomes an EFFICIENCY issue.
By eliminating it, it allows a higher quality reproduction.
Additionally, because the human ear is also most efficient at the 400hz band you eliminate harmonics associated with that bandwidth.
Example, the human ear is efficient in that range but most of the sound inside a vehicle occur in that range.
Its harmonic noise elimination.
The common term for any sound in the 400hz range is referred to as "presence"
1:16 pm EST
6:16 pm GMT
Very basic speaker circuits tried had to deal with this issue with a
Creating a "crossover" to eliminate certain very efficient frequency.
By using a resistor...to charge a capacitor... They create a "time phasing circuit" that will not allow certain frequencies to "PASS"
The next iteration was called a "crossover"
Where you elimate the frequency pass in the pre-amp stage.(before it is amplified.
Once again, it is an EFFICIENCY issue ....
Why amplify harmonics?
1:23 pm EST
6:23 pm GMT
Started manufacturing rotor blades to utilize the sound harmonic as an amplifier.
Because a motor that is harmonic, is a reciprocating assembly.
(A speaker is a motor).....
Then the science turned to eliminating that harmonic with "inverse sound waves"
I think in the end it was decided that the sound of a helicopter harmonic was much more terrifying to the enemy........
.......than a quiet strike.
1:28 pm EST
6:28 pm GMT
Point being, it's an equilibrium of the effect you are trying to create.
If you want people scared, play the tone(and utilize the harmonics)
If you want a peaceful and enjoyable experience, eliminate them.
But, That could be said about anything.