Publication | Closed Access
Effects of spectral smearing on the intelligibility of sentences in noise
191
Citations
0
References
1993
Year
Speech StimuliSpeech IntelligibilityPsycholinguisticsAuditory DevelopmentSpeech ScienceComputational LinguisticsNoiseAuditory ScienceLanguage StudiesHealth SciencesAuditory ProcessingCognitive ScienceAuditory ModelingCognitive Hearing ScienceSpeech ProductionAudiologyLinguisticsSpectral SmearingHearing DisordersAuditory ResearchHuman HearingSpeech CommunicationSpeech AnalysisHearing LossSpeech AcousticsAuditory PhysiologyHearing PerceptionSpeech ProcessingDifferent DeficitsSpeech PerceptionAuditory SystemAuditory Neuroscience
Cochlear hearing loss involves deficits such as reduced frequency selectivity, but the relative impact of this deficit on speech understanding remains unclear due to complex interactions among multiple hearing impairments. The study investigates how reduced frequency selectivity influences speech intelligibility by simulating spectral smearing of sentences. Spectral smearing was applied to sentences using an overlap–add method to generate excitation patterns that mimic impaired auditory filters, with several smearing types varying in breadth and asymmetry, and the resulting stimuli were tested for intelligibility in quiet and speech‑shaped noise with normal‑hearing listeners. Spectral smearing had little effect on intelligibility in quiet, even with filters six times broader than normal, but markedly degraded intelligibility in noise, especially at low SNRs and with large smearing, and lower‑side asymmetrical broadening produced a greater decline than upper‑side broadening, highlighting the role of upward spread of masking.
Cochlear hearing loss is generally associated with a variety of deficits in the ability to analyze sounds, including reduced frequency selectivity. The complex interrelationships between the different deficits have made it difficult to assess the contribution of reduced frequency selectivity to the difficulties experienced by hearing-impaired people in understanding speech. To address this question, the effects of reduced frequency selectivity on the place representation of speech stimuli in the auditory system were simulated by ‘‘smearing’’ the spectra of the stimuli, using the overlap–add method. The smearing was designed to evoke excitation patterns in a normal ear that would resemble those evoked in an impaired ear using unsmeared stimuli. Several different types of smearing were used, simulating specific degrees of broadening and asymmetry of the auditory filter. Sentences in quiet and in speech-shaped noise were smeared and presented to normally hearing listeners in intelligibility tests. The results showed that the intelligibility of speech in quiet was hardly affected by spectral smearing, even for smearing that simulated auditory filters six times broader than normal. However, the intelligibility of speech in noise was adversely affected by the smearing, especially for large degrees of smearing and at a low speech-to-noise ratio (−3 dB). Simulation of asymmetrical broadening of the lower side of the auditory filter had a greater effect than simulation of asymmetrical broadening of the upper side, suggesting that upward spread of masking may be particularly important.