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At least 595 records · Page 33Linked to original sources
PubMed1999

Endotracheal intubation, but not laryngeal mask airway insertion, produces reversible bronchoconstriction.

BACKGROUND: Tracheal intubation frequently results in an increase in respiratory system resistance that can be reversed by inhaled bronchodilators. The authors hypothesized that insertion of a laryngeal mask airway would be less likely to result in reversible bronchoconstriction than would insertion of an endotracheal tube. METHODS: Fifty-two (45 men, 7 women) patients were randomized to receive a 7.5-mm (women) or 8-mm (men) endotracheal tube or a No. 4 (women) or No. 5 (men) laryngeal mask airway. Anesthesia was induced with 2 microg/kg fentanyl and 5 mg/kg thiopental, and airway placement was facilitated with 1 mg/kg succinylcholine. When a seal to more than 20 cm water was verified, respiratory system resistance was measured immediately after airway placement. Inhalation anesthesia was begun with isoflurane to achieve an end-tidal concentration of 1% for 10 min. Respiratory system resistance was measured again during identical conditions. RESULTS: Among patients receiving laryngeal mask airways, the initial respiratory system resistance was significantly less than among patients with endotracheal tubes (9.2+/-3.3 cm water x 1(-1) x s(-1) [mean +/- SD] compared with 13.4+/-9.6 cm water x 1(-1) x s(-1); P < 0.05). After 10 min of isoflurane, the resistance decreased to 8.6+/-3.6 cm water x 1(-1) x s(-1) in the endotracheal tube group but remained unchanged at 9.1+/-3.3 cm water x 1(-1) x s(-1) in the laryngeal mask airway group. The decrease in respiratory system resistance in the endotracheal tube group of 4.7+/-7 cm water x 1(-1) x s(-1) was highly significant compared with the lack of change in the laryngeal mask airway group (P < 0.01). CONCLUSIONS: Resistance decreased rapidly only in patients with endotracheal tubes after they received isoflurane, a potent bronchodilator, suggesting that reversible bronchoconstriction was present in patients with endotracheal tubes but not in those with laryngeal mask airways. A laryngeal mask airway is a better choice of airway to minimize airway reaction.

Anesthesia↗
PubMed1999

Use of the cuffed oropharyngeal airway as an alternative to the laryngeal mask airway with positive-pressure ventilation.

BACKGROUND: The cuffed oropharyngeal airway is a modified Guedel-type oral airway with a cuff at its distal end. The objectives of this study were to compare the ability of the cuffed oropharyngeal airway and the laryngeal mask airway to provide positive-pressure ventilation during general anesthesia, and to assess their relative ease of use and ability to reduce total fresh gas flow rates. METHODS: In this prospective, randomized study, a cuffed oropharyngeal airway (n = 25) or a laryngeal mask airway (n = 25) device was inserted after induction of anesthesia intravenously using 2 mg/kg propofol. While anesthesia was maintained with sevoflurane and nitrous oxide, the leak pressure, leak fraction (the fractional difference between the inspired and expired tidal volume), minimum fresh gas flow rate, and need for airway manipulations were determined. The anesthesia provider who inserted the device completed an evaluation form at the end of the 15-min study period. RESULTS: Positive-pressure ventilation was established successfully on the first attempt in 92% of the patients when the cuffed oropharyngeal airway was used and in 88% of the patients when the laryngeal mask airway device was used. However, manipulations of the airway device were necessary more frequently (8 vs. 1 patient; P < 0.05) and the leak pressure was less (22 +/- 6 cm water vs. 26 +/- 5 cm water; P < 0.05) with the cuffed oropharyngeal airway than with the laryngeal mask airway. In addition, the leak fraction (0.19 +/- 0.18 vs. 0.31 +/- 0.22; P < 0.05) and the minimum fresh gas flow rate (1.3 +/- 1.5 vs. 2.4 +/- 2.5; P = 0.12) were less in the laryngeal mask airway group. CONCLUSIONS: Positive-pressure ventilation is possible with the laryngeal mask airway and cuffed oropharyngeal airway devices. Although the cuffed oropharyngeal airway can be inserted easily by inexperienced users with a high first-attempt success rate (> 90%), manipulations of the device may be required to maintain a patent airway. The laryngeal mask airway device allows positive-pressure ventilation at slightly greater peak inspiratory pressures.

Adult↗
PubMed2002

Masks depicting hemifacial microsomia and cleft lip.

All masks are created by craftspeople. Accordingly, most masks are generally predictable in dimensions, and the portraitures usually depict the faces and heads of humans. The authors found some masks representing the features of craniofacial anomalies, such as hemifacial microsomia and, rarely, cleft lip. Reviewing the legends of wearing masks with a medley of grotesque features, the authors could deduce the tone of society in those days. A mask, "crooked mouth," of Native Americans shows typical lineament of hemifacial microsomia. The deformity of the face was legendarily regarded as resulting from trauma caused by either "one's fault" or a "curse of God." "Yangban" (noblemen of aristocratic class) customarily wore the cleft lip mask in age-old Korean masquerade revels. Laymen ridiculed Yangban by making cleft lip masks for them. The authors presume that the victims of craniofacial deformities were treated contemptuously at that time.

Cleft Lip↗
PubMed1993

Comparison of mask and nasal continuous positive airway pressure after extubation and mechanical ventilation.

OBJECTIVE: To examine the effects of continuous positive airway pressure applied via face masks and nose masks on the change in functional residual capacity and gas exchange. DESIGN: Descriptive and prospective study. SETTING: Intensive care unit of a university hospital. PATIENTS: Ten patients with acute lung injury who had required mechanical ventilation. INTERVENTIONS: Continuous positive airway pressure at a level of 10 cm H2O applied in random order via face and nose masks. MEASUREMENTS AND MAIN RESULTS: Both continuous positive airway pressure methods resulted in an almost identical increase of functional residual capacity. During nasal continuous positive airway pressure, the increase in functional residual capacity was 294 +/- 82 mL. During mask continuous positive airway pressure, the increase in functional residual capacity was 290 +/- 85 mL. PaO2 increased and the alveolar-arterial oxygen tension/alveolar oxygen tension quotient decreased significantly during mask continuous positive airway pressure and nasal continuous positive airway pressure at a level of 10 cm H2O. Two patients showed a periodic change in their breathing patterns; they took a few breaths at an increased lung volume, followed by one deep expiration caused by mouth opening. Change in mask pressure was negligible in these two patients. Using a visual analog scale (10 = highly comfortable; 0 = severely uncomfortable), the patients rated nasal continuous positive airway pressure (8.6 +/- 0.9) significantly more comfortable than mask continuous positive airway pressure (2.6 +/- 0.8). CONCLUSION: The major advantages of continuous positive airway pressure (the improvement of functional residual capacity and oxygen transfer) can also be achieved with nasal continuous positive airway pressure in the postextubation period in patients who have been mechanically ventilated for acute lung injury.

Acute Disease↗
PubMed1998

The effects of broadband noise masking on cortical event-related potentials to speech sounds /ba/ and /da/.

OBJECTIVE: To systematically investigate in normal-hearing listeners the effects of decreased audibility produced by broadband noise masking on the cortical event-related potentials (ERPs) N1, N2, and P3 to the speech sounds /ba/ and /da/. DESIGN: Ten normal-hearing adult listeners actively (button-press response) discriminated the speech sounds /ba/ and /da/ presented in quiet (no masking) or with broadband masking noise (BBN), using an ERP oddball paradigm. The BBN was presented at 50, 60, and 70 dB SPL when speech sounds were presented at 65 dB ppe SPL and at 60, 70 and, 80 dB SPL when speech sounds were presented at 80 dB ppe SPL. RESULTS: On average, the 50, 60, 70, and 80 dB SPL BBN maskers produced behavioral threshold elevations of 18, 25, 35, and 48 dB (average for 250 to 4000 Hz), respectively. The BBN maskers produced significant decreases (relative to quiet condition) in ERP amplitudes and behavioral discriminability. These decreases did not occur, however, until the noise masker intensity (in dB SPL) was equal to or greater than the speech stimulus intensity (in dB ppe SPL), that is, until speech to noise ratios (SNRs) were < or = 0 dB. N1 remained present even after N2, P3, and behavioral discriminability were absent. In contrast to amplitudes, ERP and behavioral latencies showed significant decreases at higher (better) SNRs. Significant latency increases occurred when the noise maskers were within 10 to 20 dB of the stimuli (i.e., SNR < or = 20 dB). The effects of masking were greater for responses to /da/ compared with /ba/. Latency increases occurred with less masking for N1 than for P3 or behavioral reaction time, with N2 falling in between. CONCLUSIONS: These results indicate that decreased audibility as a result of masking affects the various ERP peaks in a differential manner and that latencies are more sensitive indicators of these masking effects than are amplitudes.

Adult↗
PubMed1999

Aided growth of masking for speech and nonspeech signals.

OBJECTIVE: Growth of masking (GOM) functions for speech and nonspeech signals were obtained in normal and impaired ears, with an emphasis on aided listening conditions. The purpose of the investigation was to determine whether electroacoustic contrasts between hearing aid circuits would manifest themselves in aided GOM functions and to determine whether amplification alters the slopes of GOM functions in impaired ears. DESIGN: Five normal-hearing and 10 hearing-impaired listeners with sloping high-frequency losses participated. GOM functions were obtained in the sound field using a two-interval forced choice forward masking paradigm. Four sets of test signals consisted of narrowband noise maskers and sinusoidal probes. Two additional stimulus sets consisted of phonemes used as masker and probe. Both on-frequency and off-frequency masking conditions were examined. Test circuits included wide dynamic range compression (low compression threshold and low compression ratio) and output compression limiting (high compression threshold and high compression ratio), each adjusted to the DSL[i/o] prescriptive target. GOM slopes were calculated for normal-hearing and hearing-impaired subjects unaided, and for impaired subjects aided, in an effort to determined whether amplification compensates for abnormal growth of masking and whether electroacoustic contrasts between circuits differentially affect level-dependent masker effectiveness. RESULTS: Results indicated large differences between normal and impaired functions unaided. Under aided conditions, narrowband noise masked thresholds were reduced re: unaided at lower masker levels but not at higher masker levels. Masked thresholds for phoneme maskers were reduced at all masker levels. In general, aided GOM slopes changed in the direction of normal but did not match normal slopes. Aided results were highly dependent on stimulus test conditions and were consistent with the compression thresholds and release times of the aids under test. Circuit contrasts were more apparent when phonemes were used as masker and probe than when conventional signals were used. CONCLUSION: Results suggest that GOM functions can be altered by amplification in ways that are consistent with the electroacoustic characteristics of the circuits being used. Although these data address only a small number of conditions, they suggest a possible application for aided growth of masking in the evaluation of hearing aid performance.

Adult↗
PubMed1993

Stability in backward masking performance in schizophrenics, affectively disturbed patients, and normal subjects.

The purpose of the present longitudinal study was to investigate the stability of backward masking performance in schizophrenics and nonschizophrenic psychotic patients. Twenty-two schizophrenics, eight nonschizophrenics, and 14 normal controls were tested three times, with an interval of 1 year between each test session. A standard stimulus duration procedure was used. The relative onset intervals between the target and the mask was 16.5 msec or 33 msec. A no mask condition was presented before the two masking conditions. Results showed that masking performance is a stable phenomenon, for both psychiatric groups and for normal controls. Significant differences were found between schizophrenics and the normal controls, but not between the two psychiatric groups. Vulnerability to masking stimuli as a specific characteristic for schizophrenics is, thus, not supported in the present study. The results suggest that backward masking deficit is an enduring feature of psychotic disturbances.

Adult↗
PubMed2004

Airway protection and the laryngeal mask airway in sinus and nasal surgery.

OBJECTIVES/HYPOTHESIS: The objective was to compare the laryngeal mask airway and endotracheal tube for airway protection from blood during sinonasal surgery. STUDY DESIGN: Nonrandomized, controlled, prospective clinical trial. METHODS: Patients scheduled to undergo sinonasal surgery (septoplasty and/or endoscopic sinus surgery) were prospectively enrolled and grouped according to type of airway during general anesthesia with choice of airway device based on the anesthesiologist's preference. Clinical data were tabulated by case including airway device, patient age, weight, estimated blood loss, airway pop-off pressure, and emergence quality. At the conclusion of surgery, the airway was examined through the laryngeal mask airway or endotracheal tube with a flexible fiberoptic bronchoscope to determine the amount of blood present on the vocal cords or in the trachea. The airway device was also evaluated postoperatively for the presence of blood. RESULTS: Seventy-six adult patients were initially enrolled; two were excluded because fiberoptic evaluation of the airway could not be completed. Of the remaining 74 patients, an endotracheal tube and laryngeal mask airway were used in 31 and 43 patients, respectively. The two groups did not differ with respect to age, weight, estimated blood loss during surgery, pop-off pressure, or emergence quality (all P >.05). Patients managed with an laryngeal mask airway were significantly less likely to have blood staining the airway (glottis or trachea) than patients with an endotracheal tube (19.5% vs. 84.8%, chi test [P <.001]). However, the endotracheal tube provided better protection than the laryngeal mask airway against distal tracheal blood contamination (3.2% vs. 14.6%, respectively [P =.110]). CONCLUSION: The laryngeal mask airway provides better protection of the upper airway from blood contamination during sinonasal surgery than a standard endotracheal tube, but there is a higher incidence of distal tracheal contamination. The laryngeal mask airway is a reasonable alternative to endotracheal intubation for airway management in sinonasal surgery.

Adult↗
PubMed1994

Processing speed in the cerebral cortex and the neurophysiology of visual masking.

In experiments to investigate the duration of the time for which cortical neurons respond when the identification of a visual stimulus is just possible, we presented a test face stimulus for 16 ms, and followed it at different intervals by a masking stimulus (either an N-O pattern or a face) while recording from single neurons in the temporal visual cortex of macaques. When there was no mask the cells responded to the 16 ms of the test stimulus for 200-300 ms, far longer than the presentation time. We suggest that this reflects the operation of a short-term memory system implemented in cortical circuitry. If the mask was a stimulus which did not stimulate the cells (either a non-face pattern or a face which was a non-effective stimulus for that cell), then, as the interval between the onset of the test stimulus and the onset of the mask stimulus (the stimulus onset asynchrony) was reduced, the length of time for which the cells fired in response to the test stimulus was reduced. It is suggested that this is due to the mask stimulating adjacent cells in the cortex which by lateral inhibition reduce the responses of the cells activated by the test stimulus. When the stimulus onset asynchrony was 20 ms, face-selective neurons in the inferior temporal cortex of macaques responded for a period of 20-30 ms before their firing was interrupted by the mask. With the same test-mask stimulus onset asynchrony of 20 ms, humans could just identify which of six faces was shown.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

A new laryngeal mask prototype. Preliminary evaluation of seal pressures and glottic isolation.

A new prototype laryngeal mask airway is described which incorporates a second mask to isolate the upper oesophagus and a second dorsal cuff to increase the seal against the glottis. We have made a within-patient comparison of seal pressures between the prototype and standard laryngeal mask airway in 20 patients, and determined if the prototype facilitates functional isolation of the glottis and upper oesophagus. Leak pressure was found to be significantly higher for the prototype and equalled or exceeded 5.0 kPa in all patients (p < 0.001). The prototype laryngeal mask airway provided functional isolation in all patients as judged by leak and placement of a gastric tube via the oesophageal mask. Ease of insertion and incidence of pharyngeal morbidity appeared similar to the standard laryngeal mask, but were not formally tested. The prototype laryngeal mask airway exhibits potentially useful new features which justify further evaluation and development.

Adult↗
PubMed1997

Damage to the laryngeal mask by residual fluid in the cuff.

It has been suggested that, in some situations, the cuff of the laryngeal mask should be filled with fluid. We speculated that this practice might damage the device during sterilisation in an autoclave. We studied whether injection of a small volume of water into the cuff of the laryngeal mask and subsequent sterilisation affected the integrity of the cuff. First, a pressure-volume relationship for each of 20 new masks was obtained by inflating the cuff with increasing volumes of air (5-45 ml). The masks were then randomly allocated into four groups (W0, W0.25, W0.5 or W1.0), 0, 0.25, 0.5 or 1.0 ml of water was injected into the cuff and the mask was then sterilised in an autoclave. After sterilisation, the shape of the cuff was examined and pressure-volume relationships were obtained again. The baseline intracuff pressures were similar in the four groups. After sterilisation, the pressure was significantly lower in groups W0.25, W0.5 and W1.0 than in group W0 (p < 0.05). Two masks in group W1.0 lost their integrity, resulting in herniation of and rupture of the cuff. We conclude that the cuff of the laryngeal mask should not be inflated with fluid unless the device is discarded afterwards.

Equipment Failure↗
PubMed1995

Prevention of asthma induced by cold air by cellulose-fabric face mask.

We have tested the effect of a porous cellulose fabric face mask. Nine asthmatic patients, anamnestically sensitive to cold, took part in exercise tests on an ergometer bicycle at a temperature of approximately -10 degrees C, with and without a face mask. For comparison, exercise tests were also performed with breathing taking place through a woolen scarf. Three minutes after finishing the exercise test, there was an average fall in FEV1 of 32% in the group without a face mask. The corresponding fall in FEV1 was 6% with a face mask and 17% with a scarf. In order to get some idea of the patients' attitudes to the face mask, it was used by 25 asthma patients during a period of 2 weeks in winter, after which they were asked to answer a simple questionnaire. Eighty-eight percent of the patients stated that the face mask had provided satisfactory protection against asthma complaints induced by cold air, and 72% reported that they had been able to spend more time out-of-doors. The results show that porous cellulose fabric designed as a face mask offers effective protection against asthma complaints induced by cold air and exercise, and that the patients appear to appreciate this protective aid highly despite the cosmetic disadvantages.

Adult↗
PubMed2006

Flow-dependent resistance of nasal masks used for non-invasive positive pressure ventilation.

OBJECTIVE AND BACKGROUND: Endotracheal tube resistance is known to be flow-dependent and this understanding has improved the application of invasive ventilation. However, similar physiological studies on the interface between patients and non-invasive positive pressure ventilation (NPPV) have not been performed. Therefore, this study was aimed at investigating the resistance of nasal masks used for NPPV. METHODOLOGY: The flow-dependent pressure drop of the small (S), medium-small (MS) and medium (M) Contour Nasal Mask (Respironics Inc., Murrysville, PA, USA) was measured with and without a connecting tube (length 18 cm, internal diameter 1.5 cm) in a laboratory study. The resistance was calculated by Rohrer's equation using the standard least-squares-fit technique. The present study explicitly differentiated between the resistance of the nasal mask alone when measured against atmosphere and the additional resistance caused by the nasal mask when airtightly fitted to a model head (interaction with the face). RESULTS: Higher flow rates resulted in a non-linearly increasing pressure drop across the interface. This flow-dependent resistance of the S/MS/M mask was comparably low when not interacting with the face, but increased when interacting with the face. This flow-dependent resistance of the mask was several-fold higher when adding the connection tube and tended to be higher during expiration. CONCLUSION: There is a non-linear flow-dependent pressure drop across the nasal mask which is low and independent of its size, but increases when interacting with the face. The connecting tube is the major determinant of the resistance originating from facial appliances used for NPPV.

Airway Resistance↗
PubMed1999

Backward masking performance as an indicator of vulnerability to schizophrenia.

Several types of design have been used to identify neurocognitive measures that indicate vulnerability to schizophrenia rather than the presence of the illness. These designs include studies of first-degree relatives of patients, studies of patients in symptomatic remission, and studies of subjects who are considered to be prone to psychosis. The backward masking procedure is one promising indicator of vulnerability to schizophrenia. Backward masking is a procedure in which identification of an initial stimulus (the target) is disrupted by a later stimulus (the mask). Schizophrenic patients show performance deficits on backward masking. Unaffected siblings of patients, remitted patients, and individuals prone to psychosis also show performance deficits on backward masking. This pattern of results suggests that backward masking is a promising indicator of vulnerability to schizophrenia. It provides an alternative phenotype for schizophrenia that is separate from the disorder. The composite nature of masking procedures helps investigators to parse a performance deficit into its smallest meaningful elements and relate them to vulnerability to schizophrenia.

Attention↗
PubMed2002

Similarity, uncertainty, and masking in the identification of nonspeech auditory patterns.

This study examined whether increasing the similarity between informational maskers and signals would increase the amount of masking obtained in a nonspeech pattern identification task. The signals were contiguous sequences of pure-tone bursts arranged in six narrow-band spectro-temporal patterns. The informational maskers were sequences of multitone bursts played synchronously with the signal tones. The listener's task was to identify the patterns in a 1-interval 6-alternative forced-choice procedure. Three types of multitone maskers were generated according to different randomization rules. For the least signal-like informational masker, the components in each multitone burst were chosen at random within the frequency range of 200-6500 Hz, excluding a "protected region" around the signal frequencies. For the intermediate masker, the frequency components in the first burst were chosen quasirandomly, but the components in successive bursts were constrained to fall in narrow frequency bands around the frequencies of the components in the initial burst. Within the narrow bands the frequencies were randomized. This masker was considered to be more similar to the signal patterns because it consisted of a set of narrow-band sequences any one of which might be mistaken for a signal pattern. The most signal-like masker was similar to the intermediate masker in that it consisted of a set of synchronously played narrow-band sequences, but the variation in frequency within each sequence was sinusoidal, completing roughly one period in a sequence. This masker consisted of discernible patterns but not patterns that were part of the set of signals. In addition, masking produced by Gaussian noise bursts--thought to produce primarily peripherally based "energetic masking"--was measured and compared to the informational masking results. For the three informational maskers, more masking was produced by the maskers comprised of narrow-band sequences than for the masker in which the frequencies were not constrained to narrow bands. Also, the slopes of the performance-level functions for the three informational maskers were much shallower than for the Gaussian noise masker or for no masker. The findings provided qualified support for the hypothesis that increasing the similarity between signals and maskers, or parts of the maskers, causes greater informational masking. However, it is also possible that the greater masking was a consequence of increasing the number of perceptual "streams" that had to be evaluated by the listener.

Adult↗
PubMed2003

Multiple bursts, multiple looks, and stream coherence in the release from informational masking.

In the simultaneous multitone masking paradigm introduced by Neff and Green [Percept. Psychophys. 41, 409-415 (1987)] the masker typically is a small number of tones having frequencies and levels that are randomly drawn on every presentation. Large amounts of masking for a pure-tone signal often occur that are thought to reflect central, rather than peripheral, limitations on processing. Previous work from this laboratory has indicated that playing a rapid succession of randomly drawn multitone maskers in each observation interval dramatically reduces the amount of masking that is observed relative to a single burst (SB). In this multiple-bursts-different (MBD) procedure, the signal tone is the only constant frequency component during the sequence of bursts and tends to perceptually segregate from the masker. In this study, the number of masker bursts and the interburst interval (IBI) were varied. The goals were to determine how the release from masking relative to the SB condition depends on the number of bursts and to examine whether increasing the IBI would cause each burst to be processed independently. If the latter were true, it might disrupt the perception of signal stream coherence, thereby diminishing the MBD advantage. However, multiple independent looks could also lead to an improvement in performance. For those subjects showing large amounts of informational masking in the SB condition, substantial reduction in masked thresholds occurred as the number of masker bursts increased, while masking increased as IBI lengthened. The results were not consistent with a simple version of a multiple-look model in which the information from each burst was combined optimally, but instead appear to be attributable to mechanisms involved in the perceptual organization of sounds.

Adolescent↗
PubMed2006

Phase effects in masking by harmonic complexes in birds.

Masking by harmonic complexes depends on the frequency content of the masker and its phase spectrum. Harmonic complexes created with negative Schroeder phases (component phases decreasing with increasing frequency) produce more masking than those with positive Schroeder phases (increasing phase) in humans, but not in birds. The masking differences in humans have been attributed to interactions between the masker phase spectrum and the phase characteristic of the basilar membrane. In birds, the similarity in masking by positive and negative Schroeder maskers, and reduced masking by cosine-phase maskers (constant phase), suggests a phase characteristic that does not change much along the basilar papilla. To evaluate this possibility, the rate of phase change across masker bandwidth was varied by systematically altering the Schroeder algorithm. Humans and three species of birds detected tones added in phase to a single component of a harmonic complex. As observed in earlier studies, the minimum amount of masking in humans occurred for positive phase gradients. However, minimum masking in birds occurred for a shallow negative phase gradient. These results suggest a cochlear delay in birds that is reduced compared to that found in humans, probably related to the shorter avian basilar epithelia.

Acoustic Stimulation↗
PubMed2006

Isolating the energetic component of speech-on-speech masking with ideal time-frequency segregation.

When a target speech signal is obscured by an interfering speech wave form, comprehension of the target message depends both on the successful detection of the energy from the target speech wave form and on the successful extraction and recognition of the spectro-temporal energy pattern of the target out of a background of acoustically similar masker sounds. This study attempted to isolate the effects that energetic masking, defined as the loss of detectable target information due to the spectral overlap of the target and masking signals, has on multitalker speech perception. This was achieved through the use of ideal time-frequency binary masks that retained those spectro-temporal regions of the acoustic mixture that were dominated by the target speech but eliminated those regions that were dominated by the interfering speech. The results suggest that energetic masking plays a relatively small role in the overall masking that occurs when speech is masked by interfering speech but a much more significant role when speech is masked by interfering noise.

Adolescent↗