Intelligibility Of Interrupted Speech Research Articles

Effect of F0 contours on top-down repair of interrupted speech.

Top-down repair of interrupted speech can be influenced by bottom-up acoustic cues such as voice pitch (F0). This study aims to investigate the role of the dynamic information of pitch, i.e., F0 contours, in top-down repair of speech. Intelligibility of sentences interrupted with silence or noise was measured in five F0 contour conditions (inverted, flat, original, exaggerated with a factor of 1.5 and 1.75). The main hypothesis was that manipulating F0 contours would impair linking successive segments of interrupted speech and thus negatively affect top-down repair. Intelligibility of interrupted speech was impaired only by misleading dynamic information (inverted F0 contours). The top-down repair of interrupted speech was not affected by any F0 contours manipulation.

Effect of language experience on the intelligibility of interrupted speech

Signal distortions are more detrimental to speech perception by native than non-native listeners. We investigated how speech clarity and semantic context influence the perception of interrupted speech. Native and non-native American English listeners heard semantically meaningful or anomalous sentences produced as conversational or “clear” speech, gated at different rates (0.5–16 Hz). Results showed that both semantic context and speech clarity had a significant rate-dependent impact on the intelligibility of interrupted speech. In general, intelligibility was higher for native than non-native listeners. However, the magnitude of the clear-speech benefit varied across the two listener groups. The clear-speech benefit was obtained for gating rates of 2 Hz and above, except for meaningful sentences with native listeners where the benefit begin at 1 Hz. Both listener groups were able to use contextual information but native listeners derived more benefit at lower gating rates, indicating greater ability to access semantic information with limited acoustic-phonetic input. The results suggest that the non-native speech-perception deficit in adverse listening conditions may in part be due to their less efficient use of compensatory information at higher levels of language processing.

Intelligibility of interrupted speech in listeners of different age and hearing status

In most real-world communicative environments, speech signals are fragmented and incomplete due to masking by other concurrent sounds. Experiments in the perception of gated and time-compressed speech provide a useful approach for systematically investigating factors involved in the perception of temporally fragmented speech. In the current work, the intelligibility of spoken sentences was measured following periodic signal interruption at various square-wave gating rates with time compression applied by either omitting or doubling silent intervals during gated-off times. Across interruption rates (0.5–16 Hz), speech perception of younger and older normal-hearing and older hearing-impaired adults was similar for slow interruption rates, but differed substantially for the faster rates. This rate-dependent variation was consistently found for different interruption methods and conditions. Importantly, speech perception at fast interruption rates correlated strongly with pure-tone thresholds and performance on speech-in-noise tests, while it did not correlate with results from tests of working memory or spectro-temporal pattern discrimination. These findings suggest that different perceptual processes are involved in the perception of interrupted speech at slow and at faster interruption rates, and have implications for developing diagnostic tests applicable to real-world listening environments. [Work supported by NIH.]

Effect of speech clarity on perception of interrupted meaningful and anomalous sentences

The influence of speech clarity on the perception of interrupted speech was examined for sentences distinguished by the presence of semantic-contextual cues. Semantically meaningful and anomalous sentences produced in either conversational or speech were periodically interrupted at gating rates ranging from slow (0.5 Hz) to fast (24 Hz) and presented to 26 native English listeners. At slow rates, speech perception may be based on integration of whole syllables and words, with glimpsing of (sub)phonemic segments playing a role at faster rates. Our results show that semantic context and speech clarity had a significant rate-dependent impact on the intelligibility of interrupted speech. At the lowest rates, intelligibility differences between conditions were minimal. Overall, interruption was most deleterious for anomalous conversational sentences. Such effects were seen even at the highest gating rate of 24 Hz for which interruption effects are generally minimal. The magnitude of the clear-speech benefit varied with gating rate for the two types of sentences, starting at 1 Hz for meaningful and 2 Hz for anomalous sentences. Acoustic-phonetic enhancements of clear speech thus shifted contextual benefit to lower gating rates. The implications of these results for our understanding of different time scales of speech processing will be discussed.

Phonemic restoration in sensorineural hearing loss does not depend on baseline speech perception scores

The brain can restore missing speech segments using linguistic knowledge and context. The phonemic restoration effect is commonly quantified by the increase in intelligibility of interrupted speech when the silent gaps are filled with noise bursts. In normal hearing, the restoration effect is negatively correlated with the baseline scores with interrupted speech; listeners with poorer baseline show more benefit from restoration. Reanalyzing data from Başkent et al. [(2010). Hear. Res. 260, 54-62], correlations with mild and moderate hearing impairment were observed to differ than with normal hearing. This analysis further shows that hearing impairment may affect top-down restoration of speech.

Intelligibility of interrupted speech in normal‐hearing listeners and cochlear implantees

The intelligibility of a target speech signal is substantially degraded in the presence of a competing talker in cochlear implantees. The current study aimed to test whether this degradation is caused by an inability to i) make use of the partial target speech information glimpsed into the competing talker valleys, and ii) fuse perceptually those successive glimpses into coherent speech streams. This hypothesis was tested by assessing the intelligibility of periodically interrupted vowel‐consonant‐vowel (VCV) signals pronounced by a male (F0=113 Hz) and female (F0=216 Hz) speaker in normal‐hearing listeners and implantees. A 4‐Hz square‐wave modulator with random phase was used to interrupt periodically each signal. The interrupted VCVs from each speaker were either presented alone (Experiment 1) or interleaved (Experiment 2: the two speakers were alternated). In experiment 1, the mean identification score calculated for each voice was about 90% in normal‐hearing listeners, and 40% in implantees. In experiment 2, the mean identification score corresponding to correct identification of both voices was about 50% in normal‐hearing listeners, but at chance level in implantees. Taken together, these data suggest that implantees can make use of partial speech information, but cannot organize this partial speech information into coherent streams.

Influences of auditory object formation on phonemic restoration

In phonemic restoration, intelligibility of interrupted speech is enhanced when noise fills the speech gaps. When the broadband envelope of missing speech amplitude modulates the intervening noise, intelligibility is even better. However, this phenomenon represents a perceptual failure: The amplitude modulation, a noise feature, is misattributed to the speech. Experiments explored whether object formation influences how information in the speech gaps is perceptually allocated. Experiment 1 replicates the finding that intelligibility is enhanced when speech-modulated noise rather than unmodulated noise is presented in the gaps. In Experiment 2, interrupted speech was presented diotically, but intervening noises were presented either diotically or with an interaural time difference leading in the right ear, causing the noises to be perceived to the side of the listener. When speech-modulated noise and speech are perceived from different directions, intelligibility is no longer enhanced by the modulation. However, perceived location has no effect for unmodulated noise, which contains no speech-derived information. Results suggest that enhancing object formation reduces misallocation of acoustic features across objects, and demonstrate that our ability to understand noisy speech depends on a cascade of interacting processes, including glimpsing sensory inputs, grouping sensory inputs into objects, and resolving ambiguity through top-down knowledge.

Effects of periodic masker interruption on the intelligibility of interrupted speech

When listeners hear a target signal in the presence of competing sounds, they are quite good at extracting information at instances when the local signal-to-noise ratio of the target is most favorable. Previous research suggests that listeners can easily understand a periodically interrupted target when it is interleaved with noise. It is not clear if this ability extends to the case where an interrupted target is alternated with a speech masker rather than noise. This study examined speech intelligibility in the presence of noise or speech maskers, which were either continuous or interrupted at one of six rates between 4 and 128 Hz. Results indicated that with noise maskers, listeners performed significantly better with interrupted, rather than continuous maskers. With speech maskers, however, performance was better in continuous, rather than interrupted masker conditions. Presumably the listeners used continuity as a cue to distinguish the continuous masker from the interrupted target. Intelligibility in the interrupted masker condition was improved by introducing a pitch difference between the target and speech masker. These results highlight the role that target-masker differences in continuity and pitch play in the segregation of competing speech signals.

Intelligibility of interrupted meaningful and nonsense speech with and without intervening noise.

The insertion of noise in the silent intervals of interrupted speech has a very striking perceptual effect if a certain signal-to-noise ratio is used. Conflicting reports have been published as to whether the inserted noise improves speech intelligibility or not. The major difference between studies was the level of redundancy in the speech material. We show in the present paper that the noise leads to a better intelligibility of interrupted speech. The redundancy level determines the possible amount of improvement. The consequences of our findings are discussed. in relation to such phenomena as continuity perception and pulsation threshold measurement. A hypothesis is formulated for the processing of interrupted stimuli with and without intervening noise: for stimuli presented with intervening noise, the presence in the auditory system of an automatic interpolation mechanism is assumed. The mechanism operates only if the noise makes it impossible to perceive the interruption.

Intelligibility of Reiterated Speech

An attempt is made to increase the intelligibility of speech sampled in time (interrupted speech) by filling in the blank spaces with repetitions of the speech samples (reiterated speech). The experiment involves the evaluation of these processes of speech distortion in quiet and in noise with two duty cycles (speech-time fractions), with various rates of interruption of the speech signal, and with various buildup and decay times in the switching operation. The results indicate that (1) there is little difference between the intelligibility of reiterated speech and interrupted speech in quiet, (2) reiterated speech is more intelligible than interrupted speech in noise if signal measurements are based on instantaneous amplitudes of the speech samples, and (3) buildup and decay has little effect on the intelligibility of interrupted speech when the entire buildup phase is confined to the “on” time of the switching period.