Wyrazistość logatomów prezentowanych na tle szumu mowopodobnego dla osób z niedosłchem typu 'martwe pola' w zakresie wysokich czestotliwości

This paper is concerned with effects of lowpass filtering on the intelligibility of speech in noise for listeners with dead regions at high frequencies. The speech stimuli were vowel-consonant-vowel (VCV) nonsense syllables, using one of three vowels (/i/, /a/ and /u/) and 21 different consonants. They were presented in speech shaped noise. The stimuli were subjected to the frequency-gain characteristic prescribed by the "Cambridge" formula. Then, the speech was lowpass filtered with various cutoff frequencies. For subjects without a dead region, performance improved progressively with increasing cutoff frequency. This indicates that they benefited from high-frequency information. For subjects with a dead region, two patterns of performance were observed. For most subjects, performance improved with increasing cutoff frequency until the cutoff frequency was up to 70% above the estimated edge frequency of the dead region, but hardly changed with further increases. Thus, these subjects were not able to benefit from the addition of high-frequency information, but the amplification of these frequencies did not impair performance for them. For other subjects, performance improved with increasing cutoff frequency until the cutoff frequency was about an octave above the estimated edge frequency of the dead region, but worsened with further increases in cutoff frequency. This indicates that amplification of high frequencies impaired performance.