This tutorial explores the almost universal appeal which the pipe organ, in instrument unique to Western culure, ecerts on the hearts and minds of humans. The subject is approached from five different perspectives; the musicologist, the listener, pipe organ craftsmen, the orgainstn, and the scientist seeking to understand the physics of pipe emerges; each in his own way, discovers intrinsic enjoyment and fulfillment in the expression of his art.

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A new unified method of treating the sounding mechanism of organ pipes and cavity resonators replaces the control volume method which until recently has been the most widely accepted theory. It is shown that shear layers contain a dividing surface whose motions control the production of sound in the resonant cavity. Both jet-drive andforce drive contributions are found to be involved in the sounding mechanism. The present approach shows the drive system to be inherently linear over a range of shear layer widths, so that sinusoidal oscillation is readily achievable. For voicing situa tionscalling for spectra rich in harmonics, nonlinear drive is attained by resorting to a smaller ratio of jet width to lip cutup which, at high enough Reynolds number, permits the growth of eddies which result in impulsive action at the lip.

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The peripheral auditory system is often modelled as containing an array of bandpass filters (called the auditory filters), each tuned to a different centre frequency. When a subject tries to detect, or discriminate changes in, a narrowband signal in noise, it has traditionally been assumed that performance is based on the output of the single audi toryfilter which gives the highest signal-to-masker ratio. However, recent experi mentsdemonstrate that outputs from other filters, tuned to frequencies remote from the signal frequency, can both enhance and degrade signal detection and discrimination. The enhancement takes place especially when the envelope of the masker fluctuates over time, and when the fluctuations are correlated across different frequency bands. This phenomenon is called comodulation masking release (CMR). In other situations, frequency components remote from the frequency of a signal may impair the discrimina tionof changes in that signal, especially changes in the modulation of the signal. This has been called modulation detection interference or modulation discrimination inter ference (MDI). Both CMR and MDI may depend partly on basic processes of audi torygrouping that are involved in assigning elements of complex sounds to perceptual streams. However, other processes are probably involved.

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A new model for describing articulatory organization is proposed, demonstrating the possibility to basically deviate from the traditional segment-concatenation coarticula tiontheory. This Converter/Distributor (C/D) Model is based on syllables as the concatenative units, and combines feature-based specifications of demisyllables with a novel concept of syllable and boundary strength and timing represented by abstract impulses. Consonantal gestures, superimposed upon a vocalic base function, are implementedas a combination of stored impulse response functions for individual elementalgestures, in respective articulatory dimensions associating actions with articulators.The C/D model is intended for description and explanation of natural speech, and emphasis is placed on its ability to handle articulatory variability due to a wide variety of extraphonological as well as prosodic effects according to simple principles.

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A series of experiments was conducted concerning the loudness and timbre of broad bandnoise mixed with frequency-modulated sounds. The results suggested the follow ings:(1) FM sounds overlapped on broad-band noise can be just detectable when S/N is around zero (S: the level of FM sound, N: the 1/3 octave band level of broad-band noise with center frequency corresponding to carrier frequency of FM sound).(2) FM sounds overlapped on broad-band noise can be detected at S/N of-10 dB or less when it is interrupted.(3) The loudness of broad-band noise shows good correspondence with Leq. However, when a prominent frequency component, such as FM sounds, is included, loudness level based on ISO 532B (LLz) shows better correspondence than Leq.(4) The timbre becomes deteriorated when the level of specific frequency component in creasesor when its frequency becomes high. These effects were found even when the overall values of L_eq were kept constant. Neither L_eq nor LLz is sufficient for evaluating these effects. The method for calculating sharpness proposed by von Bismarck is an ap propriatemethod for evaluating the metallic aspect of the timbre.

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