The yield of alkenols and cycloalkenols is substantially improved by carrying out the reaction of olefins with formaldehyde in the presence of selected catalysts. In accordance with one embodiment, alk-3-en-1-ols are produced in good yields from isobutylene and formaldehyde in the presence of organic carboxylic acid salts of Group IB metals.

The Organization of the Cochlear Receptor

This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented using vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the common mathematical models used for representing these devices. Algorithms for processing color images for display and communication are surveyed, and a forecast of research trends is attempted. An extensive bibliography is provided.

Digital color imaging

High-quality variable-rate image compression is achieved by segmenting an image into regions of different sizes, classifying each region into one of several perceptually distinct categories, and using a distinct coding procedure for each category Segmentation is performed with a quadtree data structure by isolating the perceptually more important areas of the image into small regions and separately identifying larger random texture blocks Since the important regions have been isolated, the remaining parts of the image can be coded at a lower rate than would be otherwise possible High-quality coding results are achieved at rates between 035 and 07 b/p depending on the nature of the original image, and satisfactory results have been obtained at 025 b/p >

Image compression with variable block size segmentation

A hearing compensation system for the hearing impaired comprises a plurality of bandpass filters having an input connected to an input transducer and each bandpass filter having an output connected to the input of one of a plurality of multiplicative AGC circuits whose outputs are summed together and connected to the input of an output transducer. The multiplicative AGC circuits attenuate acoustic signals having a constant background level without the loss of speech intelligibility. The identification of the background noise portion of the acoustic signal is made by the constancy of the envelope of the input signal in each of the several frequency bands. The background noise that will be suppressed includes multi-talker speech babble, fan noise, feedback whistle, fluorescent light hum, and white noise.

Hearing aid device incorporating signal processing techniques

The invention relates to the measurement and control of the perceived sound loudness and/or the perceived spectral balance of an audio signal. An audio signal is modified in response to calculations performed at least in part in the perceptual (psychoacoustic) loudness domain. The invention is useful, for example, in one or more of: loudness-compensating volume control, automatic gain control, dynamic range control (including, for example, limiters, compressors, expanders, etc.), dynamic equalization, and compensating for background noise interference in an audio playback environment. The invention includes not only methods but also corresponding computer programs and apparatus.

Calculating and adjusting the perceived loudness and/or the perceived spectral balance of an audio signal

A model is proposed which mathematically transforms an acoustic stimulus into a form which is believed to be more nearly related to that used by the auditory cortex to interpret the sound. The model is based upon research towards understanding the response of the human auditory system to sound stimuli. The motivation and approach in developing this model follow the philosophy pursued in the development of a similar model to the problem of hearing compensation for impaired individuals is shown to yield a bank of bandpass filters each followed by a homomorphic multiplicative AGC. Clinical tests on hearing impaired subjects suggest that this approach is far superior to other current hearing compensation schemes.

Application of a human auditory model to loudness perception and hearing compensation

A method of vector quantization which uses a color model of the human visual system to improve the quality of encoded images is presented. In this method, the images are first transformed into a 'perceptual space' and then encoded. After reconstruction, the image is transformed back into an intensity representation for viewing. A comparison is made between images encoded at 1.125 bits per pixel with and without the visual model using both an SNR measure and visual observation. Experimental results indicate that there is a significant improvement in the perceived quality of the images encoded in the visual model, although the measured distortion between the images is slightly better for the intensity encoded images. >

Vector quantization of color digital images within a human visual model

A method of vector quantization which uses a color model of the human visual system to improve the quality of encoded im- ages is presented. In this method, the images are first transformed into a "perceptual space" and then encoded. After reconstruction, the image is transformed back into an intensity represen- tation for viewing. A comparison is made between images en- coded at 1.125 bits per pixel with and without the visual model using both a SNR measure and visual observation. Experimental results indi- cate that there is a sigxiflcant improvement in the perceived quality of the images encoded in the visual model, although the measured distor- tion between the images is slightly better for the intensity encoded images.

http://ieeexplore.ieee.org/iel2/723/5035/00196710.pdf

Thomas G. Stockham

Papers

Hearing aid device incorporating signal processing techniques

Application of a human auditory model to loudness perception and hearing compensation

Vector quantization of color digital images within a human visual model

Images within a human visual model