Elizabeth Cohen

Pitch processing of nonharmonic tones: A search for an auditory mechanism that recognizes spectral patterns

Experiments on tone fusion [E. A. Cohen, J. Acoust. Soc. Am. Suppl. 1 65, S123 (1979); 66, 530 (1980); K. T. Marcus, M. V. Mathews, and J. R. Pierce, J. Acoust. Soc. Am. 66, 542 (1980)] suggested that tonal unity (fused pitch) is assured if the necessary and sufficient condition of a systematic overtone structure is met. The series fn′ = KAlog2nf1 was employed to insure the availability of structured harmonic and unharmonic partials. The 2nd partial of this series was deleted and a subject allowed to insert it by means of a tunable oscillator. If we are capable of recognizing nonharmonic systems then subjects should place the missing partial in the position called for by the mathematical order of the partials. Limited evidence for this ability was revealed (within ±5% of harmonic position). The results also show limited evidence for a subjective stretch of the octave when the 2nd partial is determined. It was observed that subjects (all trained musicians) experienced a remarkable, degree of difficulty eve...

Fusion and consonance relations for tones with inharmonic partials

Tones with inharmonic partials were generated on the Sampson Digital Synthesizer according to the algorithm. Fn = F1alog 2n, where Fn is the frequency of the nth partial and a determines the degree of stretching/shrinking of the octave. Subjects noted a bell or gonglike quality for stretched and shrunk tones. Subjects were asked to make judgments on the degree of fusion (unitary sensation of pitch). For individual tones a “pulling apart” of tones as a function of increasing a was discovered. Dyads, triads, melodic, and harmonic passages were also presented. Melodic relationships seem to hold throughout the range of 60% shrunk to 200% stretched (a = 1.2 → a = 4), whereas certain harmonic relationships break down. Preliminary results indicate that this harmonic breakdown is due to context and is not an individual property of the chord.

The challenges of archiving networked‐based multimedia performances (Performance cryogenics)

Music archives and libraries have cultural preservation at the core of their charters. New forms of art often race ahead of the preservation infrastructure. The ability to stream multiple synchronized ultra‐low latency streams of audio and video across a continent for a distributed interactive performance such as music and dance with high‐definition video and multichannel audio raises a series of challenges for the architects of digital libraries and those responsible for cultural preservation. The archiving of such performances presents numerous challenges that go beyond simply recording each stream. Case studies of storage and subsequent retrieval issues for Internet2 collaborative performances are discussed. The development of shared reality and immersive environments generate issues about, What constitutes an archived performance that occurs across a network (in multiple spaces over time)? What are the families of necessary metadata to reconstruct this virtual world in another venue or era? For exampl...

The effect of envelope on fusion of tones with inharmonic partials

Temporal envelopes for tones with an inharmonic partial structure were generated using the Systems Concepts Digital synthesizer. [E. Cohen, J. Acoust. Soc. Am. Suppl. 1, 65, S123(A) (1979)]. The reasons for choosing envelopes based on musical viability rather than a flat “psychoacoustically standard” pattern, will be discussed. Subjects were asked to make judgments on the degree of tone dispersion for single tones differing in degree of inharmonicity and temporal envelope. The importance of attack and decay times, as well as transients in the signal will be explained. A real‐time experiment on the determination of subjective interval size of dyads using two different envelope patterns also revealed that duration of the “steady state” portion of signal has an effect on tone fusion.

Stretched tones with only octave partials: The unsanctified octave

Stretched‐octave tones whose only partials are stretched octave partials were generated on the Sampson Digital Synthesizer according to the relation Fn = anFo. where n = 1,2,4…. These partials are separated by distances greater than a critical band yet subject reports of difference in tone quality suggest an interaction among the partials. For a = 2. a tone with octave partials only has been traditionally perceived as thin and clear. [J. R. Pierce, J. Acoust. Soc. Am. 40, 249 (1966); IRCAM communication, April 1976]. Departures from a = 2 show progressively greater variance from this percept. The expected beats of mistuned octaves are heard in these tones only with great difficulty and under special conditions. An explanation for the change in tone quality was sought by looking at the rate of phase change between partials. Reasons for interaction phenomena in such widely stretched partials are discussed.

The digital preservation facility

Critical listening should be an essential part of all archiving and restoration facilities quality control. We review the priorities and requirements for listening spaces ranging from the individual collector and small community archives to large‐scale facilities. Examples discussed include the Library of Congress Culpepper facility, university libraries, and commercial facilities. Adapting listening rooms to the requirements of n‐channel audio are discussed. Public recommendations of the Sound Preservation Board of the Library of Congress will be reviewed.

Electroacoustic design of the Hollywood Bowl sound reinforcement system

This renovation began in 1988 with replacement of loudspeaker arrays used primarily for music reinforcement including orchestra, chorus, soloists, jazz ensembles, etc. The system was expanded to three discrete channels above the stage. Goals realized were improvements in the sound‐pressure level uniformity, fidelity, gain before feedback, and spatial image. Several novel techniques were employed. The techniques include: (1) frequency selective filtration among multiple like drivers in a single channel to reduce audible phase interference; and (2) the introduction of delayed signal from the “far” channel into the center channel, so that extreme house right can hear left channel and vice versa. The second phase of the renovation involved replacement of the signal chain downstream of the mixing desk output, resulting in further enhancement of peak output levels. Currently, the transducers and signal chain before and at the mixing desk are being examined.

Digital recording techniques involving vocal and percussion ensembles: The Gyuto Tantric Monks

The Gyuto Tantric Monks use handbells, cymbals, damaru (skull drums), rejong (double‐membrane wood drums), horns, and long trumpets to summon their deities. Their chants consist of slowly recited Sanskrit texts. They are able to produce and sustain harmonic chords over long periods of time [Smith et al., J. Acoust. Soc. Am. 41, 5 (1967)]. They produce a music of unparalleled dynamic range. The disparity between the voices and the drums offers a unique challenge to the recording engineer. The Monks were recorded on several occasions in May of 1985. We developed techniques for both live stereo and studio multitrack digital recording. Individual and ambience miking techniques will be discussed. Shared, dynamic, fastomiking techniques for live recordings will be explored. Methods for balancing recording requirements with PA demands will also be discussed. The results of spectral analysis of the recordings confirm the level of fidelity obtained.

The contemporary state of percussion acoustics in China

This paper reports on the results of the authors visits to the Peoples Republic of China. The authors visited and performed with percussion sections of the opera and National Orchestras. A comparison of the regional differences in instrument design and construction has been made, comparing Wuhan, Beijing, and Kiangsu. The evolution of gong and bell design is discussed. Development and design control of ancient mallets and sticks is also contrasted to contemporary instruments.

The influence of signal processing devices on the timbre perception of electric guitars

Spectral analysis at several stages of the output of Ibanez Custom Built Fender Telecaster, and Fender Stratocaster guitars have been completed. The signals were examined in a multiplicity of pickup configurations, including both single and double coil. We examined the direct output from pickups and studied the coloration due to the addition of the following devices: reverberation units, parametric equalizers, compressor/limiters, analog delay, flanging, and phase controllers. They were studied both with the entire relay system in the circuit and with the not so common, but preferable, hardwire bypass, enabling all switching effects to be eliminated from a system. Tones were produced by plucking strings with plectrums of different materials, and allowing the strings to vibrate over the magnet‐coil systems. Steel slides and bottle slides were also used to initiate tone production. Tone control settings were varied. These experiments have shown that visualization of the signal and correlation of the signal,...