Suppression of acoustic noise in speech using two microphone adaptive noise cancellation

technical reportAcoustic noise with energy greater or equal to the speech is suppressed by filtering a separately recorded correlated noise signal and subtracting it from the speech waveform. This approach was investigated to determine the degree of noise suppression possible using an external correlated input. The second reference noise signal is adaptively filtered using the least mean squares, LMS and the lattice gradient algorithms. These two approaches are developed and compared in terms of degree of noise power reduction, algorithm convergence time, and degree of speech enhancement. Both methods were shown to reduce ambient noise power by at least 20dB with minimal speech distortion and thus to be potentially powerful as noise suppression preprocessors for voice communication in severe noise environments

Application of adaptive noise cancellation to noise reduction in audio signals

technical reportThe LMS adaptive noise cancellation algorithm has been applied to the removal of high-level white noise from audio signals. Simulations and actual acoustically recorded signals have been processed successfully, with excellent agreement between the results obtained from simulations and the results obtained with acoustically produced data. A study of the filter length required in order to achieve a desired noise reduction level in a hard-walled room is presented. The performance of the algorithm in this application is described and required modifications are suggested. A multichannel processing scheme is presented which allows the adaptive filter to converge at independent rates in different frequency bands. This is shown to be of particular use when the interfering noise is not white. Careful implementation of the scheme allows the problem to be broken into several smaller ones which can be handled by independent processors, thus allowing longer filter lengths to be processed in real time

Peripheral-Blood Stem Cells versus Bone Marrow from Unrelated Donors

BACKGROUND Randomized trials have shown that the transplantation of filgrastim-mobilized peripheral-blood stem cells from HLA-identical siblings accelerates engraftment but increases the risks of acute and chronic graft-versus-host disease (GVHD), as compared with the transplantation of bone marrow. Some studies have also shown that peripheral-blood stem cells are associated with a decreased rate of relapse and improved survival among recipients with high-risk leukemia. METHODS We conducted a phase 3, multicenter, randomized trial of transplantation of peripheral-blood stem cells versus bone marrow from unrelated donors to compare 2-year survival probabilities with the use of an intention-to-treat analysis. Between March 2004 and September 2009, we enrolled 551 patients at 48 centers. Patients were randomly assigned in a 1:1 ratio to peripheral-blood stem-cell or bone marrow transplantation, stratified according to transplantation center and disease risk. The median follow-up of surviving patients was 36 months (interquartile range, 30 to 37). RESULTS The overall survival rate at 2 years in the peripheral-blood group was 51% (95% confidence interval [CI], 45 to 57), as compared with 46% (95% CI, 40 to 52) in the bone marrow group (P=0.29), with an absolute difference of 5 percentage points (95% CI, −3 to 14). The overall incidence of graft failure in the peripheral-blood group was 3% (95% CI, 1 to 5), versus 9% (95% CI, 6 to 13) in the bone marrow group (P=0.002). The incidence of chronic GVHD at 2 years in the peripheral-blood group was 53% (95% CI, 45 to 61), as compared with 41% (95% CI, 34 to 48) in the bone marrow group (P=0.01). There were no significant between-group differences in the incidence of acute GVHD or relapse. CONCLUSIONS We did not detect significant survival differences between peripheral-blood stem-cell and bone marrow transplantation from unrelated donors. Exploratory analyses of secondary end points indicated that peripheral-blood stem cells may reduce the risk of graft failure, whereas bone marrow may reduce the risk of chronic GVHD. (Funded by the National Heart, Lung, and Blood Institute–National Cancer Institute and others; ClinicalTrials.gov number, NCT00075816.

Health-Related Quality of Life among Older Related Hematopoietic Stem Cell Donors (>60 Years) Is Equivalent to That of Younger Related Donors (18 to 60 Years): A Related Donor Safety Study

The increasing number of older adults with blood-related disorders and the introduction of reduced intensity conditioning regimens has led to increases in hematopoietic stem cell (HSC) transplantation among older adults and a corresponding increase in the age of siblings who donate HSCs to these patients. Data regarding the donation-related experiences of older donors is lacking. The Related Donor Safety Study (RDSafe) aimed to examine/compare health-related quality of life (HRQoL) of older versus younger HSC donors. 60 peripheral blood stem cell (PBSC) donors ages 18–60 and 104 PBSC donors age >60 completed validated questionnaires at pre-donation, 4 weeks and 1 year post-donation. Prior to donation, older donors had poorer general physical health (t=−3.27; p=.001) but better mental health (t=2.11; p<.05). There were no age differences in multiple other donation-related factors. At 4 weeks post-donation, there were no group differences in general physical/mental health, but older donors were less likely to report donation-related pain (t=−2.26; p<.05) and concerns (t=−3.38; p=.001). At both 4 weeks and 1 year post-donation, there were no significant differences in the percentage of each age group feeling physically back to normal or in the number of days it took donors to feel completely well. There was no evidence that increasing age within the older donor group was associated with poorer donation-related HRQoL. Taken together, these data support the current practice of HSC donation by sibling donors above age 60, providing no evidence of worsening HRQoL up to one year after donation in individuals up to age 76

Significant Improvements in the Practice Patterns of Adult Related Donor Care in US Transplantation Centers

Recent investigations have found a higher incidence of adverse events associated with hematopoietic cell donation in related donors (RDs) who have morbidities that if present in an unrelated donor (UD) would preclude donation. In the UD setting, regulatory standards ensure independent assessment of donors, one of several crucial measures to safeguard donor health and safety. A survey conducted by the Center for International Blood and Marrow Transplant Research (CIBMTR) Donor Health and Safety Working Committee in 2007 reported a potential conflict of interest in >70% US centers, where physicians had simultaneous responsibility for RDs and their recipients. Consequently, several international organizations have endeavored to improve practice through regulations and consensus recommendations. We hypothesized that the changes in the 2012 FACT-JACIE Standards, resulting from the CIBMTR study, will have significantly impacted practice. Accordingly, a follow-up survey of US transplant centers was conducted to assess practice changes since 2007, and investigate additional areas where RD care was predicted to differ from UD care. 73 centers (53%), performing 79% of US RD transplants responded. Significant improvements were observed since the earlier survey; 62% centers now ensure separation of RD and recipient care (P<0.0001). However, this study identifies several areas where RD management does not meet international donor care standards. Particular concerns include counseling and assessment of donors before HLA typing, with 61% centers first disclosing donor HLA results to an individual other than the donor, the use of unlicensed mobilization agents, and the absence of long-term donor follow-up. Recommendations for improvement are described

Analysis of the Effect of Race, Socioeconomic Status, and Center Size on Unrelated National Marrow Donor Program Donor Outcomes: Donor Toxicities Are More Common at Low-Volume Bone Marrow Collection Centers

Previous studies have shown that risks of collection-related pain and symptoms are associated with sex, body mass index (BMI), and age in unrelated donors undergoing collection at National Marrow Donor Program (NMDP) centers. We hypothesized that other important factors (race, socioeconomic status (SES), and number of procedures at the collection center) might affect symptoms in donors. We assessed outcomes in 2,726 bone marrow (BM) and 6,768 peripheral blood stem cell (PBSC) donors collected between 2004 and 2009. Pain/symptoms are reported as maximum levels over mobilization and collection (PBSC) or within 2 days of collection (BM) and at 1 week after collection. For PBSC donors, race and center volumes were not associated with differences in pain/symptoms at any time. PBSC donors with high SES levels reported higher maximum symptom levels 1 week post donation (p=0.017). For BM donors, black males reported significantly higher levels of pain (OR=1.90, CI=1.14-3.19, p=0.015). No differences were noted by SES groups. BM donors from low volume centers reported more toxicity (OR=2.09, CI=1.26-3.46, p=0.006). In conclusion, race and SES have a minimal effect on donation associated symptoms. However, donors from centers performing ≤1 BM collection every 2 months have more symptoms following BM donation. Approaches should be developed by registries and low volume centers to address this issue

Noise suppression methods for robust speech processing (1 April 1979- 30 Sept. 1979)

technical reportRobust speech processing in practical operating environments requires effective environmental and processor noise suppression. This report describes the technical findings and accomplishments during this reporting period for the research program funded to develop real-time, compressed speech analysis-synthesis algorithms whose performance is invariant under signal contamination. Fulfillment of this requirement is necessary to insure reliable secure compressed speech transmission within realistic military command and control environments. Overall contributions resulting from this research program include the understanding of how environmental noise degrades narrow band, coded speech, development of appropriate real time noise suppression algorithms, and development of speech parameter identification methods that consider signal contamination as a fundamental element in the estimation process. This report describes the current research and results in the areas of noise suppression using the dual input adaptive noise cancellation using the LMS and gradient lattice algorithms, to spectral analysis and synthesis using the constant -Q trans form, articulation rate change techniques, analytic continuation of band limited signals or signal extrapolation, and two-dimensional automatic gain control

Noise suppression methods for robust speech processing (1 Oct. 1978- 31 Mar. 1979)

technical reportRobust speech processing in practical operating environments requires effective environmental and processor noise suppression. This report describes the technical findings and accomplishments during this reporting period for the research program funded to develop real time, compressed speech analysis-synthesis algorithms whose performance is invariant under signal contamination. Fulfillment of this requirement is necessary to insure reliable secure compressed speech transmission within realistic military command and control environments. Overall contributions resulting from this research program include the understanding of how environmental from this research program include the understanding of how environmental noise degrades narrow band, coded speech, development of appropriate real time noise suppression algorithms, and development of speech parameter identification methods that consider signal contamination as a fundamental element in the estimation process. This report describes the current research and results in the areas of noise suppression using the spectral subtraction algorithm, dual input adaptive noise cancellation using the LMS algorithm, pole-zero parameter estimation, nonparametric-rank order statistics with applications to Robust Speech activity detection, spectral analysis and synthesis using the constant-Q transform, and pitch and rate changes to speech using the constant-Q transform

Noise suppression methods for robust speech processing (1 Oct. 1978- 31 Mar. 1981)

technical reportRobust speech processing in practical operating environments requires effective environmental and processor noise suppression. This report describes the technical findings and accomplishments during this reporting period for period for research program funded to develop real time, compressed speech analysis-synthesis algorithms whose performance is invariant under signal contamination. Fulfillment of this requirement is necessary to insure reliable secure compressed speech transmission within realistic military command and control environments. Overall contributions resulting from this research program include the understanding of how environmental noise degrades narrow band, coded speech, development of appropriate real time noise suppression algorithms, and development of speech parameter identification methods that consider signal contamination as a fundamental element in the estimation process. This report describes the current research and results in the areas of noise suppression using the SABER algorithm, dual input adaptive noise cancellation using the LMS algorithm, pole-zero parameter estimation, nonparametric-rank order statistics applications to Robust Speech activity detection, and spectral analysis and synthesis using the constant-Q transform