Frequency-dependent amplitude modification devices for acoustic sources

A system for generating an acoustic signal, said system comprising:

• an acoustic signal generating device (a) having a frequency response defining a frequency pass band within which acoustic signals can be generated, and (b) providing along an axis of propagation an acoustic signal output as a function of said frequency response, wherein said pass band has an upper frequency portion;
• and
• an apparatus for modifying the acoustic signal output of said acoustic signal generating device by correcting for distortion in the form of amplitude variations occurring in the upper frequency portion of said frequency pass band of the frequency response of said acoustic signal generating device and for extending the upper frequency portion of the frequency pass band of the frequency response of said acoustic signal generating device, said apparatus comprising means, positioned in the path of said acoustic signal, and shaped, dimensioned and disposed so as to (1) modify said acoustic signal in order to correct for said distortion by substantially reducing or eliminating said amplitude variations occurring in the upper frequency portion of said frequency pass band, and (2) provide an enhanced frequency response of the combination of said acoustic signal generating device and said apparatus defining a resulting frequency band wider than said frequency pass band of said acoustic signal generating device, said means positioned in said path of said acoustic signal comprising:
• a bridge element disposed in said path of said acoustic signal output transversely to said axis of propagation of said acoustic signal output so that said acoustic signal output is transmitted on each side of the bridge element so as to provide said enhanced frequency response, and
• means, disposed on the bridge element and defining openings disposed transverse to said axis of propagation, for modifying said acoustic signal in order to correct for said distortion by substantially reducing or elimination said amplitude variations occurring in the upper frequency portion of said frequency pass band.

A loudspeaker system comprising:

• (a) a loudspeaker driver having a moving diaphragm defining a speaker face, said loudspeaker driver having an output frequency response having distortions in the form of amplitude variations occurring in at least one narrow frequency band of the frequency response of the driver;
• (b) frequency response modification means comprising a plurality of hollow pipes, each pipe corresponding to and being so dimensioned, shaped, and disposed as to correct for said distortions, and means for supporting said pipes such that at least one open end of each pipe intercepts an output signal from the loudspeaker driver, and is disposed so as to cause at least a partial cancellation of said amplitude variations;
• (c) a ported speaker enclosure, cooperative with said loudspeaker driver, and subject to speaker port coloration distortion in the form of amplitude variations within a narrow frequency band of the frequency response of said enclosure, a hollow tube so dimensioned and disposed as to correct for said coloration distortion;
• and
• (d) means for mounting said tube outside said enclosure such that the axis of the tube is substantially perpendicular to the axis of the port and one open end of said tube intercepts sound propagated from said port.