SPEECH INTELLIGIBILITY TESTS WITH A VOCODER BASED ON THE HEARING SENSATION SHARPNESS.

THE PRINCIPLES OF A VOCODER BASED ON THE HEARING SENSATION SHARPNESS ARE BRIEFLY REVIEWED. DIFFERENT IMPLEMENTATIONS OFTHE SHARPNESS-VOCODER WERE REALIZED. THE BIT RATE WAS REDUCED BY A REDUCTION OF THE AMPLITUDE-CODING FROM 5 BIT TO 3 BIT AND/OR BY APPLYING A CONSTANT INSTEAD OF A VARIABLE FUNDAMENTAL FREQUENCY. THE SPEECH INTELLIGIBILITY TESTS YIELD SCORES FOR ISOLATED MONOSYLLABIC WORDS (DIN 45 621) BETWEEN 38 AND 55P AT BIT-RATES BETWEEN 1364 BIT/S AND 1864 BIT/S. FOR WORDS IN THE CONTEXT OF SENTENCES SCORES REACH 86 AND 93P, RESPECTIVELY.