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At least 127 records · Page 7Linked to original sources
PubMed2006

Performance enhancement for audio-visual speaker identification using dynamic facial muscle model.

Science of human identification using physiological characteristics or biometry has been of great concern in security systems. However, robust multimodal identification systems based on audio-visual information has not been thoroughly investigated yet. Therefore, the aim of this work to propose a model-based feature extraction method which employs physiological characteristics of facial muscles producing lip movements. This approach adopts the intrinsic properties of muscles such as viscosity, elasticity, and mass which are extracted from the dynamic lip model. These parameters are exclusively dependent on the neuro-muscular properties of speaker; consequently, imitation of valid speakers could be reduced to a large extent. These parameters are applied to a hidden Markov model (HMM) audio-visual identification system. In this work, a combination of audio and video features has been employed by adopting a multistream pseudo-synchronized HMM training method. Noise robust audio features such as Mel-frequency cepstral coefficients (MFCC), spectral subtraction (SS), and relative spectra perceptual linear prediction (J-RASTA-PLP) have been used to evaluate the performance of the multimodal system once efficient audio feature extraction methods have been utilized. The superior performance of the proposed system is demonstrated on a large multispeaker database of continuously spoken digits, along with a sentence that is phonetically rich. To evaluate the robustness of algorithms, some experiments were performed on genetically identical twins. Furthermore, changes in speaker voice were simulated with drug inhalation tests. In 3 dB signal to noise ratio (SNR), the dynamic muscle model improved the identification rate of the audio-visual system from 91 to 98%. Results on identical twins revealed that there was an apparent improvement on the performance for the dynamic muscle model-based system, in which the identification rate of the audio-visual system was enhanced from 87 to 96%.

Adult↗
PubMed1983

Movement of facial muscles following intra-cortical microstimulation (ICMS) along the lateral branch of the posterior bank of the ansate sulcus, areas 5a and 5b, in the cat.

The lateral branch of the posterior bank of the ansate sulcus within the parietal cortex, areas 5a and 5b, was mapped using intracortical microstimulation (ICMS). Motor effective sites for contraction of facial muscles were identified using ICMS currents of less than 30 microA. Of the 177 effective sites, 78% were activated with threshold currents of less than 20 microA, and of these, 33% responded to stimulus strengths of less than 10 microA. Since neurons in this portion of the ansate region send projections to the face region of motor cortex, area 4 gamma, the possibility existed that the motor effects might be mediated through area 4 gamma. To examine this possibility we ablated both the anterior sigmoid gyrus (ASG) and the second somatosensory cortex, SII, including area 2pri, a region shown to contain a low threshold motor component, and report that the motor effect recorded from the ansate region is independent of both the ASG and area 2pri.

Animals↗
PubMed1994

Responses in neck and facial muscles to sudden free fall and a startling auditory stimulus.

EMG responses elicited by sudden onset of free fall and a startling auditory stimulus were investigated in healthy subjects while lying on a couch with their eyes closed. Muscle responses were recorded from masseter (V cranial nerve), orbicularis oculi and mentalis (VII nerve) and sternomastoid and trapezoid (XI nerve). A similar sequence of muscle activation and absolute latencies occurred in response to both stimulus modalities, consisting of a blink (30 msec) followed simultaneously by mentalis, sternomastoid and trapezoid (55 msec). Masseter could either be simultaneously activated with the latter muscles or follow after a delay of 10-20 msec. A patient with bilateral cochleo-vestibular nerve section had responses at comparable latencies in the free fall experiment. The similarities between the reaction to free fall and a startling auditory stimulus indicate that the early response to free fall constitutes a startle and that various stimuli converge onto a common response generator. The latency pattern of neck and facial muscles does not follow a sequence of innervation with increasing segmental distance from a single centre. Therefore, our data do not support the concept that the startle response is produced by a caudally and rostrally spreading volley from a putative pontomedullary centre. It is suggested that the startle response is a polysynaptically generated patterned muscle activation.

Acoustic Stimulation↗
PubMed1990

Lip-length and snout indices: methods for quantitative assessment of peri-oral facial muscle strength.

Two simple bedside methods for the assessment of perioral muscle function are described. Using a marking gauge, the width of the mouth can be measured easily and accurately. Lip-length (LL) and snout (S) indices are expressions of the degree to which the width of the mouth can be lengthened or shortened. Facial muscle weakness as present in patients with various neuromuscular diseases results in low values for both indices. LL- and S-indices are measured by 3 observers in 19 healthy volunteers. Interobserver variation is negligible for the LL-index and large for the S-index. Intraobserver variation is moderate for both indices but slightly smaller for the LL- than for the S-index. The LL-index is suited for the assessment of changes in peri-oral musculature in longitudinal investigations.

Adult↗
PubMed1990

[Relation between articulatory function and prosthesis. I-1. Longitudinal changing aspects in the duration of speech sound, muscular discharge of facial muscle and tongue pressure before pronunciation caused by the experimental palatal plate].

The author noticed the relation between articulatory functions and the prosthesis. For the purpose of clarifying the influence of the insertion of denture on the duration of speech sound and the articulatory functions before pronunciation and on the self-compensation of these organs. The experimental palatal plates were inserted on 13 subjects with natural dentition, assuming that they were inserted with complete denture, and the duration of speech sound, muscular discharge of facial muscle and tongue pressure before pronunciation were evaluated longitudinally with the pre-insertion of palatal plate as basis. As the result of this study, the following conclusions were obtained. The results of this study suggest that speech sound, lips and tongue being important organs as the articulators are placed under strong influence before pronunciation by insertion of the denture, whereas on the self-compensation of the articulators before pronunciation differed according to the point of articulation and the manner of articulation of each speech sound. Therefore, it was necessary to take care on the relation between the shape of palatal plate and the articulatory functions of lips and tongue in the clinical prosthodontics.

Articulation Disorders↗
PubMed1990

Facial muscle reanimation using the trigeminal motor nerve: an experimental study in the rabbit.

Surgical repair of facial nerve deficits may be marred by lack of muscle control and donor region paresis. Using New Zealand white rabbits, a study was undertaken to evaluate facial muscle reanimation with a donor source not previously used: the motor division of the trigeminal nerve. The results were compared with the severed facial nerve and hypoglossal-facial coaptation. An atrophy scale was calibrated for facial muscles of the rabbit. Clinical, electromyographic, and histomorphometric findings confirmed that the trigeminal nerve was a suitable donor source. The neurorrhaphy produced an exponential rate of repair.

Anastomosis, Surgical↗
PubMed1991

Comparison of integrated evoked EMG between the hypothenar and facial muscle groups following atracurium and vecuronium administration.

In 17 healthy patients undergoing O2.N2O.isoflurane anaesthesia, following atracurium or vecuronium administration, we compared simultaneous integrated evoked electromyograms (IEEMGs) during spontaneous recovery of the adductor digiti minimi (ADM) and orbicularis oris (OOM) muscle groups in response to train-of-four (TOF) stimulation of the ulnar and facial nerves, respectively. In all patients, the onset of neuromuscular recovery occurred first in the OOM. The time required to recover to a T4/T1 = 0.70 +/- 0.01 (SD) was earlier in the OOM compared with the ADM muscles in both the atracurium (33.4 +/- 5 vs 46.5 +/- 8, P less than 0.005) and vecuronium (46.5 +/- 12 vs 60.3 +/- 20, P less than 0.005) groups. When the OOM attained a T4/T1 = 0.70 +/- 0.01, the simultaneous T4/T1 in the ADM was 0.29 +/- 0.15 (P less than 0.05) in the atracurium group and 0.41 +/- 0.16 (P less than 0.01) in the vecuronium group. We conclude that (1) the facial muscles (OOM) recover earlier than the hypothenar muscles (ADM) and (2) an EMG T4/T1 = 0.70 in the facial muscles may not indicate adequate recovery of neuromuscular function.

Adolescent↗
PubMed1989

Upper facial muscle activity and survival after hypoxic insult in rats.

Spontaneous cerebral biopotentials were monitored during and after hypoxic insults in 30 ketamine-anesthetized rats. Upper facial electromyographic (EMG, mean integrated amplitude) and electroencephalographic (mean zero cross frequency (ZXF) and mean integrated amplitude (MIA] data were recorded within 30 min after reoxygenation and cardiopulmonary resuscitation. The animals were separated into 2 groups based on 24 h survival. EMG in Survivors (n = 16) recovered regularly to pre-insult levels by 30 min after resuscitation. At this time, EMG activity was consistently low in Non-survivors. In contrast, ZXF and MIA, albeit sensitive hypoxia detectors, did not totally discriminate between Survivors and Non-survivors. Absent EMG in Non-survivors may have reflected irreversible hypoxic damage at the brainstem level.

Animals↗