Speech Discrimination Ability Research Articles

A Study of Speech Discrimination Ability of Cleft Palate Patients with Abnormal Articulation

A Study of Speech Discrimination Ability of Cleft Palate Patients with Abnormal Articulation

Hearing in Noise Test in Subjects With Conductive Hearing Loss

It has been reported that patients with pure conductive hearing loss (CHL) have remarked that their hearing is better in the presence of background noise. This study investigated the ability for speech discrimination under background noise in adult subjects with CHL, using the Mandarin Hearing in Noise Test (M-HINT). Seventeen subjects with unilateral CHL and 15 with bilateral CHL participated in this study. Twenty normal-hearing subjects served as controls. During the M-HINT, the sentences and noise were presented in a soundproof chamber. Reception threshold for sentences (RTS) in quiet were obtained first, and then three more blocks, including noise from the front, right and left, were measured for each subject. The RTS in quiet was significantly elevated in unilateral and bilateral CHL groups. For the unilateral group, regardless of whether noise came from the front, affected side, or normal side, the signal-tonoise ratio (SNR) that was needed to reach 50% correction was significantly higher than in the control group. For the bilateral group, the SNR for noise from the front, left and right was significantly elevated compared with that in the unilateral and control groups. The noise composite score was also significantly different among these three groups (control < unilateral < bilateral). There was reduced speech discrimination ability under background noise in adult subjects with unilateral or bilateral CHL.

Auditory Steady-State Responses and Speech Feature Discrimination in Infants

The aim of this study was to determine whether there was a correlation between auditory steady-state responses (ASSRs) for complex toneburst stimuli and speech feature discrimination (SFD) abilities in young infants. Seventeen infants (mean age = 9.4 months) and 21 adults (mean age = 27 years) with normal hearing had ASSR and SFD tests. The ASSR test employed an eight-component complex toneburst stimulus; threshold and input-output functions were determined as level was systematically varied. The SFD test utilized an observer-based, visual-reinforcement test procedure to determine the infant's ability to detect the speech feature change from /ba/ to /da/. The correlation of the group mean /ba/-/da/ discrimination performance (percent correct) with the group mean ASSR score (percent responses present) ranged from r = 0.64 for the 1500 Hz amplitude-modulated and frequency-modulated tone burst to 0.99 for ASSRs for all stimulus components; however, correlations between ASSRs and SFD scores for individual subjects were modest. The ASSR and SFD results appear to reflect the audibility of the stimuli.

Does Early Speech Discrimination Predict Language Ability?

Problem There is a paucity of instruments available to assess speech discrimination in normal-hearing (NH) and hearing-impaired (HI) infants. We assess the utility of a hybrid visual habituation paradigm (HVHP) in assessing speech discrimination and predicting later language ability. Methods NH infants were tested with the HVHP on an easier vowel contrast or a more difficult fricative contrast. Parents completed Macarthur Communicative Development Inventories (CDI) when infants were 14,18,24, and 30 months old to assess correlations between discrimination abilities and later language ability. Similarly, HVHP and CDI measures were obtained from HI infants at following hearing aid (HA) or cochlear implant (CI) use. Results 29% of NH infants significantly discriminated the vowel contrast. 6% of NH infants significantly discriminated the fricative contrast. Effect size of fricative discrimination at 9 months correlated with early gestures (n=10), r=.73 p=.02, and later gestures (n=10, r=.81 p = .01), at 14 months of age. HI infants tested on the vowel contrast at 3 months of HA use demonstrated significant correlations of effect size of discrimination with phrases understood at 6 months of HA use (n=4, r=.96, p=0.04) and vocabulary production at 9 months of HA use (n=5, r=.90, p=0.04). Conclusion The HVHP can be used with various contrasts to assess the speech discrimination abilities of NH and HI infants. While data collection is ongoing, it appears that performance on the HVHP may correlate with later language outcomes in both NH and HI infants. Significance This study assesses the utility of the HVHP in assessing speech discrimination, and is a step towards developing clinical tools to assess the progress of HI infants following early intervention. Support Supported by a 2007 AAO-HNSF Resident Research Award and NIH grant R01DC6235 to Indiana University.

Cortical activity patterns predict speech discrimination ability

Neural activity in the cerebral cortex can explain many aspects of sensory perception. Extensive psychophysical and neurophysiological studies of visual motion and vibrotactile processing show that the firing rate of cortical neurons averaged across 50-500 ms is well correlated with discrimination ability. In this study, we tested the hypothesis that primary auditory cortex (A1) neurons use temporal precision on the order of 1-10 ms to represent speech sounds shifted into the rat hearing range. Neural discrimination was highly correlated with behavioral performance on 11 consonant-discrimination tasks when spike timing was preserved and was not correlated when spike timing was eliminated. This result suggests that spike timing contributes to the auditory cortex representation of consonant sounds.

Electric acoustic stimulation of the auditory system: results of a multi-centre investigation

Conclusion. A high rate of hearing preservation during cochlear implantation for electric acoustic stimulation (EAS) is possible, even when surgery is conducted by a number of different surgeons. Objectives. This study aimed to determine the degree of hearing preservation using surgery for EAS in a European multi-centre clinical investigation. It also aimed to demonstrate the effect of EAS in individuals with residual low frequency hearing, both on speech perception and on subjective quality of life measures. Patients and methods. Eighteen patients with profound high frequency hearing loss were recruited in five participating European centres. Subjects were assessed based on an audiologic test battery, as well as on a subjective hearing aid benefit questionnaire. Each subject underwent attempted hearing preservation cochlear implantation using the MED-EL C40+ device with a Medium electrode. Residual ipsilateral hearing and speech discrimination abilities were assessed at defined intervals up to 12 months after the combined electric-acoustic mode was introduced. Results. Results showed that some degree of hearing preservation was possible in 15718 patients. All subjects showed statistically significant benefit on all three speech perception tests over time. These significant benefits were also reflected in the subjective benefit outcomes.

Teacher ratings of children's listening difficulties

Children with developmental disorders may present with listening and/or speech discrimination difficulties. This study explores whether teachers can identify these difficulties, using a questionnaire that rates children's listening, speech discrimination and comprehension abilities. The questionnaire was given to class-teachers of 52 pupils, aged four to five years, who had failed at least one of two formal assessments of comprehension and speech discrimination. Results showed significant correlation between teacher ratings of verbal comprehension and attentive listening and test scores for verbal comprehension. There was no significant correlation between ratings and test scores for speech discrimination skills. The questionnaire's internal consistency was found to be reliable overall, but validity in measuring speech discrimination was poor.

Non-invasive acoustic neuroma treatment via Gamma Knife stereotactic radiosurgery

Non-invasive acoustic neuroma treatment via Gamma Knife stereotactic radiosurgery

The effect of perimodiolar placement on speech perception and frequency discrimination by cochlear implant users

Conclusion. Neither speech understanding nor frequency discrimination ability was better in Nucleus Contour™ users than in Nucleus 24 straight electrode users. Furthermore, perimodiolar electrode placement does not result in better frequency discrimination. Objectives. We addressed three questions related to perimodiolar electrode placement. First, do patients implanted with the Contour™ electrode understand speech better than with an otherwise identical device that has a straight electrode? Second, do these groups have different frequency discrimination abilities? Third, is the distance of the electrode from the modiolus related to frequency discrimination ability? Subjects and methods. Contour™ and straight electrode users were matched on four important variables. We then tested these listeners on CNC word and HINT sentence identification tasks, and on a formant frequency discrimination task. We also examined X-rays and measured the distance of the electrodes from the modiolus to determine whether there is a relationship between this factor and frequency discrimination ability. Results. Both speech understanding and frequency discrimination abilities were similar for listeners implanted with the Contour™ vs a straight electrode. Furthermore, there was no linear relationship between electrode–modiolus distance and frequency discrimination ability. However, we did note a second-order relationship between these variables, suggesting that frequency discrimination is worse when the electrodes are either too close or too far away from the modiolus.

A Preliminary study of speech discrimination in youth with Down syndrome

Few studies have examined the ability of individuals with learning disabilities, in general, or with Down syndrome, specifically, to discriminate speech. The purpose of this study was compare the speech discrimination abilities of eight children with Down syndrome (aged 5.7 to 12.8 years) to seven nonverbal mental‐age matched controls (aged 4.0 to 5.3 years). A computer program presented the speech discrimination task using a two‐cued alternative forced choice procedure. On each trial, the participants heard four successive synthesized speech syllables, with the first and last stimuli being the same and serving as the cue. The results indicated children with Down syndrome differed from their nonverbal mental‐age matched peers in their ability to discriminate two of the five pairs, but not in the manner predicted. The relationship between speech discrimination, phonological memory, and speech‐language development is also discussed.

Signal-to-background-ratio preferences of normal-hearing listeners as a function of music

The primary purpose of speech is to convey a message. Many factors affect the listener’s overall reception, several of which have little to do with the linguistic content itself, but rather with the delivery (e.g., prosody, intonation patterns, pragmatics, paralinguistic cues). Music, however, may convey a message either with or without linguistic content. In instances in which music has lyrics, one cannot assume verbal content will take precedence over sonic properties. Lyric emphasis over other aspects of music cannot be assumed. Singing introduces distortion of the vowel-consonant temporal ratio of speech, emphasizing vowels and de-emphasizing consonants. The phonemic production alterations of singing make it difficult for even those with normal hearing to understand the singer. This investigation was designed to identify singer-to-background-ratio (SBR) prefer- ences for normal hearing adult listeners (as opposed to SBR levels maxi-mizing speech discrimination ability). Stimuli were derived from three different original songs, each produced in two different genres and sung by six different singers. Singer and genre were the two primary contributors to significant differences in SBR preferences, though results clearly indicate genre, style and singer interact in different combinations for each song, each singer, and for each subject in an unpredictable manner.

Normal-hearing listener preferences of music as a function of signal-to-noise-ratio

Optimal signal-to-noise ratios (SNR) for speech discrimination are well-known, well-documented phenomena. Discrimination preferences and functions have been studied for both normal-hearing and hard-of-hearing populations, and information from these studies has provided clearer indices on additional factors affecting speech discrimination ability and SNR preferences. This knowledge lends itself to improvements in hearing aids and amplification devices, telephones, television and radio transmissions, and a wide arena of recorded media such as movies and music. This investigation was designed to identify the preferred signal-to-background ratio (SBR) of normal-hearing listeners in a musical setting. The signal was the singer’s voice, and music was considered the background. Subjects listened to an unfamiliar ballad with a female singer, and rated seven different SBR treatments. When listening to melodic motifs with linguistic content, results indicated subjects preferred SBRs similar to those in conventional speech discrimination applications. However, unlike traditional speech discrimination studies, subjects did not prefer increased levels of SBR. Additionally, subjects had a much larger acceptable range of SBR in melodic motifs where the singer’s voice was not intended to communicate via linguistic means, but by the pseudo-paralinguistic means of vocal timbre and harmonic arrangements. Results indicate further studies investigating perception of singing are warranted.

Gamma knife radiosurgery for acoustic neuromas performed by a neurotologist: early experiences and outcomes.

To assess early outcomes after Gamma knife radiosurgery of acoustic neuromas and other skull base tumors. Gamma knife radiosurgery is one of the available methods to treat acoustic neuromas, in addition to micro-surgical resection. Neuro-otologists have long been associated with microsurgical resection of these tumors; however, the application of Gamma knife radiosurgery to the treatment of these tumors by neuro-otologists has not been previously described. Acoustic Neuroma and Skull Base Surgery Program / Tertiary Referral Center. STUDY DESIGN/PATIENTS/INTERVENTION: Prospective clinical study of all patients treated by the senior author and our gamma knife team beginning in June 2000. Preoperative MRI, audiometry, vestibular testing and facial nerve electromyography were completed. At six-month intervals postoperatively, audiometry, caloric testing and MRI were performed to determine thresholds and speech discrimination ability, vestibular function, and the size of the tumor. From June 2000 until March 2004, 38 patients were treated, and these included 33 acoustic neuromas, two meningiomas, one glomus jugulare tumor, and two facial neuromas. Greater than 36 month follow-up was available in 7 patients, > 24 months in 24, > 12 months in 31, and > 6 months in 34 patients. Statistically significant reduction in tumor size was seen over time, and tumor control was achieved in all but two patients. Various patterns of changes in auditory function, both in threshold and speech discrimination were observed in either positive or negative directions. Preliminary experience with Gamma knife radiosurgery indicates that this treatment method represents another option for neuro-otologists to use in managing patients with skull base tumors.

Neural network simulation of habituation and dishabituation in infant speech perception

The habituation techniques used in infant speech perception studies are based on the fact that infants show renewed interest towards novel stimuli. Recent work has shown the possibility of using artificial neural networks to model habituation and dishabituation (e.g., Schafer and Mareschal, 2001). In our study we examine weather the self-organizing-feature-maps (SOM) (Kohonen, 1989) are appropriate for modeling short-term habituation to a repeated speech stimulus. We found that although SOMs are particularly useful for simulating categorization, they can be modified to model habituation and dishabituation, so that they can be applied to direct comparisons with behavioral data on infants’ speech discrimination abilities. In particular, we modified the SOMs to include additional parameters that control the relation of input similarity, lateral inhibition, and local and lateral activation between neurons. Preliminary results suggest that these parameters are sufficient for the network to simulate the loss of sensitivity of the auditory system due to the presentation of multiple tokens of a speech stimulus, as well as to model the recovery of sensitivity to a novel stimulus. The implications of this approach to infant speech perception research will be considered.

Auditory perception in auditory neuropathy: Clinical similarity with auditory verbal agnosia

The precise features of auditory perception in patients with auditory neuropathy have not been well described. In the present study, we examined auditory perception in a patient with auditory neuropathy. The patient was a right-handed 7-year-old boy. His chief complaint was delayed speech and suspected of verbal learning disability. He could talk, read and repeat rather fluently but could not understand fully what was asked. V-IQ, P-IQ and F-IQ of Wechsler Scale for Children III-R were 53, 118 and 81, respectively. Pure tone audiogram was completely normal. His speech discrimination ability was very poor. He could identify environmental sounds with visual matching. He could differentiate intensity difference but not time difference. This phenomenon was reported in patients with hemispheric symptoms. These clinical features are very similar to verbal auditory agnosia. ABR showed no response at 90dBnHL alternating clicks and tone bursts. Click evoked and distortion product otoacoustic emissions (OAE) were normal. Electrocochleogram was also normal. Motor and sensory nerve conduction velocity was completely normal. Pa of MLR and N1 of SVR were present. His diagnosis should be ‘pure type’ of auditory neuropathy or auditory nerve disease. Importance of both ABR and OAE examination should be widely announced and auditory neuropathy must be campaigned stressed to be clinical entity among personnel who take care of children with speech delay.

Auditory Temporal Processing Deficits in Children with Periventricular Brain Injury

The present study investigated whether auditory temporal processing deficits are related to the presence and/or the severity of periventricular brain injury and the reading difficulties experienced by extremely low birthweight (ELBW: birthweight <1000 g) children. Results indicate that ELBW children with mild or severe brain lesions obtained significantly lower scores on a test requiring auditory temporal order judgments than ELBW children without periventricular brain injury or children who were full-term. Structural equation modeling indicated that a model in which auditory temporal processing deficits predicted speech sound discrimination and phonological processing ability provided a better fit for the data than did a second model, which hypothesized that auditory temporal processing deficits are associated with poor reading abilities through a working memory deficit. These findings suggest that an impairment in auditory temporal processing may contribute to the reading difficulties experienced by ELBW children.

Event-related potentials during auditory language processing in congenitally blind and sighted people

While behavioral studies have documented delayed language acquisition in blind children, other studies have revealed better speech discrimination abilities for blind than sighted adults. Several brain imaging studies have provided evidence for cortical reorganization due to visual deprivation but the cerebral organization of language in blind humans is not known yet. We hypothesized that the increasing specialization of language systems normally observed during development may not take place to the same degree in blind individuals since posterior visual areas do not receive their adequate input. On the other hand, we hypothesized that blind people, due to their greater reliance upon the auditory language signal, may process speech faster than sighted people. To test these assumptions, event-related potentials were recorded while 11 congenitally blind and 11 sighted adults matched in age, gender, handedness and education were engaged in a language task. Participants listened to sentences in order to decide after each sentence if it was meaningful or not. Incongruous sentence-final words elicited an N400 effect in both groups. The N400 effect had a left-lateralized fronto-central scalp distribution in the sighted but a symmetric and broad topography in the blind. Furthermore, the N400 effect started earlier in the blind than in the sighted. Closed class compared to open class sentence middle words elicited a more pronounced late negativity in the blind than in the sighted. These results suggest that blind people process auditory language stimuli faster than sighted people and that some language functions may be reorganized in the blind.

Mismatch Negativity to Acoustic Differences Not Differentiated Behaviorally

Mismatch negativity (MMN) reportedly reflects the neurophysiologic detection of acoustic differences, rather than the phonemic categorization of speech sounds. The purpose of the present study was to determine if it is elicited by speech contrasts that are acoustically different but are not differentiated by listeners in behavioral tasks. Experimental stimuli were drawn from a synthetically generated continuum that varied in place of articulation from /da/ to /ga/. Contrasts used to elicit MMN were (a) the continuum endpoints, (b) the two-step contrast that straddled each listener's categorical boundary, and (c) a within-category contrast that was not behaviorally differentiated by any of the listeners. MMN responses were elicited by all three experimental contrasts. It appears that MMN may be an index of the neurophysiology underlying the ability or inability to discriminate the acoustic parameters necessary for speech perception, rather than a neurophysiologic correlate of behavioral speech discrimination ability. However, limitations involving identification of MMN in the responses of individual listeners confounded this interpretation.

A modification of play audiometry to assess speech discrimination ability in severe-profoundly deaf 2- to 4-year-old children.

The aim was to develop an assessment procedure that was independent of language and speech production ability, to test speech feature discrimination in severe-profoundly deaf children 2 to 4 yr of age. The procedure being trialed was adapted from existing procedures. The child was required to respond with a game-like motor response to a "change" in a speech stimulus that was being presented repeatedly through a speaker. The change occurred at randomly determined times, and false alarm responses were measured during the waiting periods (while the child waited for the change). Two- to four-yr-old normally hearing children and hearing-impaired children using hearing aids and a group of 4-yr-old hearing-impaired children using cochlear implants were assessed on the task. More than 82% of the 3- and 4-yr-old normally hearing and hearing-impaired children were able to complete the testing for the eight speech sound contrasts within three 20 minute sessions. Fifty percent of the 2-yr-old normally hearing and hearing-impaired children were able to condition and complete the task. All of the normally hearing children who completed the task successfully discriminated all speech sound contrasts. The performance of the hearing-impaired children using hearing aids was influenced by the degree of hearing loss and the type of speech contrast being tested. Similarly, the average performance of the children using cochlear implants was better for easier contrasts such as /ba/bi/ with contrasting vowel formant cues. This procedure has potential for use as a reliable clinical and research tool for assessing the development of auditory discrimination ability in 2- to 4-yr-old severe-profoundly deaf children.

Sound Lateralization and Speech Discrimination in Patients with Sensorineural Hearing Loss

Sound lateralization and speech discrimination abilities are both closely related to central auditory system function. In this study, we investigated the relationship between sound lateralization and speech discrimination in patients with sensorineural hearing loss (SNHL) of unknown aetiology or presbycusis. Interaural intensity difference (IID) and interaural time difference (ITD) discriminations were measured using a self-recording apparatus for dichotic sound presentation, and the means of bilateral maximum scores in speech discrimination tests were calculated. Subjects with normal sound lateralization had good speech discrimination scores above 70%, while those with abnormal sound lateralization had poor scores below 70%. Some patients, however, had good speech discrimination but abnormal sound lateralization. These findings were obtained in both IID and ITD discrimination tests. Furthermore, some subjects could not discriminate ITD, although all could discriminate IID. These findings suggest that sound lateralization ability may be affected more than speech discrimination in SNHL of unknown aetiology or in presbycusis.