Improving the quality of speech in the conditions of noise and interference

Abstract

The aim of the work is to present a method of intelligent modification of the speech signal with speech features expressed in noise, based on the Lombard effect. The recordings utilized sets of words and sentences as well as disturbing signals, i.e., pink noise and the so-called babble speech. Noise signal, calibrated to various levels at the speaker's ears, was played over two loudspeakers located 2 m away from the speaker. In addition, the recording session included utterances in quiet, which constitute a reference to the received speech signal analysis with the Lombard effect. As a part of the analysis, the following parameters were examined with regard to prosody: fundamental frequency F0, formant frequencies of F1 and F2, duration of the utterance, sound intensity, etc., taking into account individual sentences, words, and vowels. The PRAAT program was used to process and analyze speech signals. Next, a method for modifying speech with the features of speech spoken in noise was proposed. Subsequent analyzes have shown that noisy speech modified by the Lombard effect features is characterized by higher values of the PESQ (perceptual evaluation of speech quality) speech quality indicator compared to noisy speech without the features incorporated.

A Novel Method for Intelligibility Assessment of Nonlinearly Processed Speech in Spaces Characterized by Long Reverberation Times

“…However, it should be remembered that the best judge of speech intelligibility is the human ear. Therefore, there are many attempts to find a correlation between objective measurement results and subjective evaluation [5][6][7][8][9]. In general, the STI value can be determined using two ways, i.e., the direct method based on modulated signals or the indirect method based on the impulse response, according to IEC 60268-16 standard [10].…”

Acoustic Sensing Analytics Applied to Speech in Reverberation Conditions

“…The so-called Lombard effect is a widely known phenomenon that is induced when the speaker unconsciously changes acoustic features of uttered speech in noise conditions. Even though this effect is known from 1911, there are many studies that have analyzed Lombard speech in the last two decades [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ], especially as there are no indicators or measures that apply directly to assessing the quality of speech in such conditions [ 13 , 14 , 15 ]. In contrast, there are not too many works on the effect of reverberation on speech uttering and to what degree it affects speech intelligibility [ 16 , 17 , 18 , 19 ].…”