Barry M. G. Cheetham

Bio: Barry M. G. Cheetham is an academic researcher from University of Manchester. The author has contributed to research in topics: Speech coding & Harmonic Vector Excitation Coding. The author has an hindex of 13, co-authored 81 publications receiving 519 citations. Previous affiliations of Barry M. G. Cheetham include University of Southampton & Victoria University, Australia.

Reduction of spectral distortion in class D amplifiers by an enhanced pulse width modulation sampling process

Abstract: An enhanced sampling process which can be used to reduce spectral distortion in the output of digital pulse width modulated class D amplifiers is presented. This process arises from a generalisation of the concepts of natural and uniform sampling and can be adjusted such that the spectra produced by the process can take a number of forms for the same signal. Analytical expressions for the spectra produced by the sampling process are derived for both single and double sided modulation. The performance of the process is assessed by case studies on full bandwidth and bass to midrange audio class D amplifiers. It is shown that at carrier frequencies around 88 kHz in a full bandwidth amplifier and 44 kHz in a bass to midrange amplifier the new sampling process will result in significantly lower distortion when compared with either natural or uniform sampling.

Low rate speech coding for telecommunications

Abstract: Over the last decade major advances have been made in speech coding technology which is now widely used in international, digital mobile and satellite networks. The most recent techniques permit telephone network quality speech transmission at 8 kbit/s, but there are still demands for even lower rates and more flexible, good quality coding techniques for various network applications. This paper reviews the developments so far, and describes a new class of speech coding methods known as speech interpolation coding which has the potential to provide toll-quality, speech coding at or below 4 kbit/s.

RSA-based Certified Delivery of E-Goods Using Verifiable and Recoverable Signature Encryption

Abstract: Delivering electronic goods over the Internet is one of the e-commerce applications that will proliferate in the coming years. Certified e-goods delivery is a process where valuable e-goods are exchanged for an acknowledgement of their reception. This paper proposes an efficient security protocol for certified e-goods delivery with the following features: (1) it ensures strong fairness for the exchange of e-goods and proof of reception, (2) it ensures non- repudiation of origin and non-repudiation of receipt for the delivered e-goods, (3) it allows the receiver of e-goods to verify, during the exchange process, that the e-goods to be received are the one he is signing the receipt for, (4) it uses an off-line and transparent semi-trusted third party (STTP) only in cases when disputes arise, (5) it provides the confidentiality protection for the exchanged items from the STTP, and (6) achieves these features with less computational and communicational overheads than related protocols.

Objective assessment of hoarseness by measuring jitter.

Abstract: The objective measurement of hoarseness by measuring 'jitter' (the average percentage pitch-period variation between consecutive pitch-cycles) using an inverse filtering technique is described. Twenty-five patients with a variety of causes of hoarseness were studied, together with five individuals who had mild hoarseness induced by histamine challenge and 12 normal individuals. The mean severity of jitter in the patient group (9.8%) was significantly different from the normals. (1.04%) In addition, there was a significant correlation (R2 = 0.53; P < 0.0001) between jitter and subjective assessment of hoarseness. The mean values of jitter with histamine challenge before and after recovery (1.03%, and 1.18%) were significantly different (P < 0.0001) to the mean maximum value during the challenge (2.64%). These data suggest that jitter is an objective and repeatable measurement of hoarseness-even small changes in hoarseness in individual patients. It is likely to prove most effective for monitoring treatment response.

DSP algorithm for cough identification and counting

Abstract: Digital signal processing (DSP) is applied to the analysis of the acoustic properties of pathological cough sounds. This work emanates from a clinical study of asthmatic, cystic fibrosis and cryptogenic fibrosing alveolitis patients. The pathological vocalisations exhibit clinically inconsistent acoustic properties from one disease to another. We aim to analyse the individual cough characteristic to adapt a DSP algorithm for identifying particular coughs and distinguishing them from background noise over long periods. The application is to obtain long-term statistical measurements to allow objective assessment of the severity of cough. This will be used for comparing the effectiveness of various treatments as well as. to study the physiological characteristic of pulmonary diseases. In this work, cough identification and counting algorithm has been developed to detect and count coughs characteristic of asthma. Its accuracy has been assessed. A sensitivity of 70.5% and specificity of 98.3% were achieved.

The diagnosis and management of chronic cough

Abstract: Fig. 1.— Overview of the evaluation of chronic cough in an adult. ACE-I: angiotensin converting enzyme inhibitor; PEF: peak expiratory flow; PNDS: post-nasal drip syndrome; GORD: gastro-oesophageal reflux disease. Fig. 2.— Therapeutic algorithm. ACE: angiotensin-converting enzyme; GORD: gastro-oesophageal reflux disease. Fig. 3.— Investigational algorithm. CT: computed tomography. Fig. 4.— Diagnostic algorithm for the approach to children with chronic cough. ENT: ear, nose and throat; PFT: pulmonary function testing; BAL: bronchoalveolar lavage; CT: computed tomography; tbc: total blood count; CMV: cytomegalovirus; PCR: polymerase chain reaction; MRI: magnetic resonance imaging; NO: nitric oxide; BHR: bronchial hyperresponsiveness. CONTENTS Chronic cough, here defined as a cough of >8 weeks duration, is a common and frequently debilitating symptom 1, 2 that is often viewed as an intractable problem. However, theexperience of specialist cough clinics is that a very high success rate, in the order of 90%, can be achieved (table 1⇓) 3–15. The key to successful management is to establish a diagnosis and to treat the cause of cough. Truly idiopathic cough is rare and misdiagnosis common, particularly because of the failure to recognise that cough is often provoked from sites outside the airway. These guidelines aim to distil the lessons from these reports and provide a framework for a logical care pathway for patients with this highly disabling symptom. View this table: Table 1— Commonest causes of chronic cough in patients investigated in specialist clinics There are three common causes of chronic cough that arise from three different anatomical areas. This varied presentation explains the major reason for the success of multidisciplinary cough clinics compared with general clinics 16. As asthma, reflux and rhinitis are the realms of different specialists who have little experience in the diagnosis of conditions outside their expertise, a patient with chronic cough may not undergo full evaluation. This problem is exacerbated by the frequently atypical presentation of …