12 research outputs found
Evaluation of the Importance of Time-Frequency Contributions to Speech Intelligibility in Noise
Recent studies on binary masking techniques make the assumption that each time-frequency (T-F) unit contributes an equal amount to the overall intelligibility of speech. The present study demonstrated that the importance of each T-F unit to speech intelligibility varies in accordance with speech content. Specifically, T-F units are categorized into two classes, speech-present T-F units and speech-absent T-F units. Results indicate that the importance of each speech-present T-F unit to speech intelligibility is highly related to the loudness of its target component, while the importance of each speech-absent T-F unit varies according to the loudness of its masker component. Two types of mask errors are also considered, which include miss and false alarm errors. Consistent with previous work, false alarm errors are shown to be more harmful to speech intelligibility than miss errors when the mixture signal-to-noise ratio (SNR) is below 0 dB. However, the relative importance between the two types of error is conditioned on the SNR level of the input speech signal. Based on these observations, a mask-based objective measure, the loudness weighted hit-false, is proposed for predicting speech intelligibility. The proposed objective measure shows significantly higher correlation with intelligibility compared to two existing mask-based objective measures
The impact of reverberant self-masking and overlap-masking effects on speech intelligibility by cochlear implant listeners (L)
This is the published version, also available here: http://dx.doi.org/10.1121/1.3614539.The purpose of this study is to determine the relative impact of reverberant self-masking and overlap-masking effects on speech intelligibility by cochlear implant listeners. Sentences were presented in two conditions wherein reverberant consonant segments were replaced with clean consonants, and in another condition wherein reverberant vowel segments were replaced with clean vowels. The underlying assumption is that self-masking effects would dominate in the first condition, whereas overlap-masking effects would dominate in the second condition. Results indicated that the degradation of speech intelligibility in reverberant conditions is caused primarily by self-masking effects that give rise to flattened formant transitions
Lateral Pharyngeal Diverticulum presenting with Dysphagia
Lateral pharyngeal diverticulum (Pharyngocele) is the protrusion of pharyngeal mucosa through the pharyngeal wall, usually through either of two weak areas in the pharyngeal wall as an acquired or congenital case. Lateral diverticula are very rare and not to be mistaken for the rather more frequent and abundantly reported cases of posterior pharyngo-esophageal diverticula (Zenker`s). Here, we present a case of this very rare condition in a young boy who presented with severe dysphagia since childhood.Key words: Lateral, pharyngeal, diverticulum dysphagi
Histologic Findings of the Sinus Node and the Perinodal Area in Street Heroin Addicts, Victims of Sudden Unexpected Death
Sudden unexpected death is frequent in street heroin addicts. We
conducted a histologic study of the sinus node (SN) to offer some
evidence about the possible arrhythmogenic cause of death. Postmortem
coronary angiography and microscopic examination of the SN and the
perinodal area were performed in 50 heroin addicts (group 1) and in 50
nonaddicts (group 2), all men (16-40 years old). In heroin addicts,
fatty and/or fibrous tissue replaced SN tissue in 21 cases (42%).
Perinodal infiltration was found in 15 cases (30%). Fibromuscular
dysplasia in branches of the sinus node artery (SNA) was found in eight
cases (16%). Inflammation with focal and/or diffuse concentration of
round cells was detected in the SN in 22 cases (44%). Old mural thrombi
were also found in 13 cases (26%). The histologic changes in the SN and
perinodal area offer an explanation about the possible mechanism of
arrhythmia and sudden death in this population
Multi-microphone adaptive noise reduction strategies for coordinated stimulation in bilateral cochlear implant devices
Bilateral cochlear implant (BI-CI) recipients achieve high word recognition scores in quiet listening conditions. Still, there is a substantial drop in speech recognition performance when there is reverberation and more than one interferers. BI-CI users utilize information from just two directional microphones placed on opposite sides of the head in a so-called independent stimulation mode. To enhance the ability of BI-CI users to communicate in noise, the use of two computationally inexpensive multi-microphone adaptive noise reduction strategies exploiting information simultaneously collected by the microphones associated with two behind-the-ear (BTE) processors (one per ear) is proposed. To this end, as many as four microphones are employed (two omni-directional and two directional) in each of the two BTE processors (one per ear). In the proposed two-microphone binaural strategies, all four microphones (two behind each ear) are being used in a coordinated stimulation mode. The hypothesis is that such strategies combine spatial information from all microphones to form a better representation of the target than that made available with only a single input. Speech intelligibility is assessed in BI-CI listeners using IEEE sentences corrupted by up to three steady speech-shaped noise sources. Results indicate that multi-microphone strategies improve speech understanding in single- and multi-noise source scenarios