Apparatus amd method for increasing the intelligibility of a loudspeaker output and for echo cancellation in telephones

A telephone comprising:

• a) a reverberation unit responsive to a speech input signal for generating a reverberation signal, the reverberation unit including:
• 1) a delay unit responsive to the speech input signal for outputting delay-signal sequences where each delay-signal sequence includes a stream of delay signals falling within a reverberation period,
• 2) a multiplier unit responsive to the delay-signal sequences for multiplying the delay signals of each delay-signal sequence with a predetermined filter coefficient sequence so as to produce a reverberation sequence of weighted delay signals, wherein the filter coefficient sequence has an exponential decay pattern where the weights of the delay signals of a delay-signal sequence tend to exponentially decrease over the reverberation period, and
• 3) an adder unit for combining the weighted delay signals of each reverberation sequence to form the reverberation signal;
• and
• b) a loudspeaker responsive to the reverberation signal for outputting a sound wave having an artificial reverberation component corresponding to the reverberation signal generated by the reverberation unit.

A telephone comprising:

• a) a reverberation signal path responsive to a speech input signal for generating a reverberation signal including:
• 1) an intelligibility-information emphasizer responsive to the speech input signal for emphasizing intelligibility information of the input speech signal and for outputting an intelligibility-dense signal, and 2) a reverberation unit responsive to the intelligibility-dense signal for generating the reverberation signal;
• b) a direct signal path responsive to the speech input signal for outputting a direct signal;
• c) an adder for combining the reverberation signal and the direct signal so as to form an intelligibility-enhanced signal;
• and
• d) a loudspeaker responsive to the intelligibility-enhanced signal for outputting a sound wave having a reverberation component corresponding to the reverberation signal and a direct component corresponding to the speech input signal.

A telephone comprising:

• a) an intelligibility booster responsive to a speech input signal for generating a first intelligibility-enhanced signal and a second intelligibility-enhanced signal, the intelligibility booster including:
• 1) a first reverberation signal path responsive to the speech input signal including a first reverberation unit for generating a first reverberation signal, wherein the first reverberation signal is a component of the first intelligibility-enhanced signal,
• 2) a second reverberation signal path responsive to the speech input signal including a second reverberation unit for generating a second reverberation signal, wherein the second reverberation signal is a component of the second intelligibility-enhanced signal, and
• 3) wherein the first and second reverberation units have different impulse functions with respect to one another so as to generate different reverberation signals;
• b) a direct signal path responsive to the speech input signal for outputting a direct signal;
• c) an adder for combining the first reverberation signal and the direct signal so as to form the first intelligibility-enhanced signal, and for combining the second reverberation signal and the direct signal so as to form the second intelligibility-enhanced signal;
• d) a first loudspeaker responsive to the first intelligibility-enhanced signal for outputting a first sound wave having a first reverberation component corresponding to the first reverberation signal and a direct component corresponding to the speech input signal;
• and
• e) a second loudspeaker responsive to the second intelligibility-enhanced signal for outputting a second sound wave having a second reverberation component corresponding to the second reverberation signal and a direct component corresponding to the speech input signal.