Daniel W. Martin

Decay Rates of Piano Tones

Decay curves were recorded for an upright piano, a baby grand, and an electronic spinet. For some tones the partials were recorded separately. Decay rates for the electronic piano were measured at different levels of piano amplification. Analysis of the data reveals the degree of control exerted by the sounding board upon decay rate, particularly in the initial stage of decay. The significance of this control by the sounding board is discussed, in relation to the problem of electrical amplification of piano tones.

Directivity and the Acoustic Spectra of Brass Wind Instruments

A single‐point harmonic analysis of the pressure wave radiating from a brass instrument is inadequate as a physical expression of the instruments acoustic output. This is partly due to the dependence of the analysis upon the relative position of the receiver. A complete statement would require a rather laborious expression of the analysis as a function of position. Probably an analysis of the total power output is the simplest single expression which is an improvement over the point analysis. Measurements of the directional radiation characteristics of several instruments in an outdoor location were obtained by driving the horn electroacoustically and plotting the sound pressure field. By integration of the intensity over a sphere, a ratio is obtained between the total power of a cornet and the power of a non‐directional source having the same pressure amplitude as on the cornets axis. A curve of this ratio is used to convert from an axial pressure wave analysis to the total power analysis which is a mo...

Magnetic Throat Microphones of High Sensitivity

An analysis is made of the problem of intelligence pick‐up from anatomical vibration. Methods for measuring the actual and effective response‐frequency characteristics of the throat are described. Measurements on the variation of effective response among different subjects are discussed in connection with the concept of “oral efficiency.” Design and performance data are given for several magnetic throat microphones of relatively high sensitivity.

The Enhancement of Music by Reverberation

The tones of traditional musical instruments such as the grand piano and the pipe organ are generally heard through the medium of room acoustics. Some effects of natural room reverberation upon organ and piano tones will be described, and demonstrated by means of magnetic tape recordings. Simple electroacoustic means (described in paper number H‐6) for simulation of reverberation in the playing of music in a nonreverberant environment will also be demonstrated.

Experiments in the Analysis of a Mechanically Produced Cornet Tone

Harmonic analyses of the tone of a cornet played mechanically are made in a location (on a framework extending over the edge of a roof) which is a good approximation to a free field. The nearest surface which can reflect sound from the source to the receiver is 40 feet away. Measurements on the radial dependence of intensity from a small source indicate that reflected sound is negligible. The microphone can be moved continuously in both azimuth and radius in order to study the directional characteristics of the horn. Preliminary measurements show that for high pitches, the total intensity changes very little until the azimuth is nearly 60°, when a sharp decrease occurs. Consideration of the geometry of the bell of the instrument would predict this effect. Furthermore, it is apparent that the spectrum changes appreciably as the angle with the axis of the horn increases, due presumably to the greater directional effect in the higher harmonics. Comparison of the analysis of the mechanically produced tone wit...

Supplementary Sound for Opera

A supplementary sound system was one of the technical innovations of the 1961 summer season of grand opera at the Cincinnati Zoo Pavilion, a covered but unenclosed area seating 2500 people. Neither the 85‐piece orchestra nor the Metropolitan and European soloists and the chorus required or were provided sound re‐enforcement. The versatile, flexible sound‐amplification and reproduction system was intended and used instead for a variety of supplementary purposes as follows: (a) auditory relocation of individual instruments or groups from the orchestra pit (actual) to backstage or on‐stage (apparent) positions, to fulfill dramatic requirements; (b) solo voice modification and motion, when “supernatural” timbre or spatial effects were appropriate; (c) sound effects which were difficult for the orchestra percussionists to produce as realistically or dramatically as desired; (d) electronic musical instruments. Microphones in the orchestra pit and backstage, stereo tape playback, and a Baldwin electronic organ w...

Factors Contributing to the Multiple Decrement of Piano Tone Envelope

The decrease in decrement of piano tone envelope with tone duration has been reported previously. Possible causes of the rate change have now been investigated, including the following: different rates for different groups of vibration modes; nonlinearity of transformation of mechanical energy to acoustical energy; storage of mechanical energy for subsequent acoustical radiation; transfer of energy between string modes perpendicular and parallel to the bridge; interference between strings which are almost exactly in tune; and change in rate of energy transfer from the multiple‐string source, before and after transition from an initial in‐phase condition to a later out‐of‐phase condition. The suggestion of the last factor and its theoretical basis was the specific contribution of Dr. Benioff. The last two factors, which are closely related, were found to control the rate change in most cases.

Fundamental Acoustics of Electronic Organ Tone Radiation

The acoustical effects achieved and the techniques used in the radiation of organ tone are quite different from the conventional effects and practices of public‐address sound systems. For the latter, point‐source radiation with high uniform directivity and a minimum of reverberation are sought, in general, for the creation of the illusion of “presence” of the original sound source. However in organ music the sound sources and their images are widely distributed in space. This is especially true in those typical cases where the tone sources are enclosed in an organ chamber, or are installed in a highly reverberant environment. Another distinctive feature of organ tone radiation systems is the relative importance of the octave below 60 cps. This paper contains design principles for electronic organ tone chambers and describes several types of organ tone cabinets now in use. Examples of the application of organ installation principles are given.

The Effects of Music Hall Acoustics Upon Grand Piano Tone

Single keys of a concert‐grand piano were actuated by an automatic mechanical blow‐striker. Magnetic tape recordings were made of the piano tones in Music Hall (Cincinnati), with the recording microphone located at selected positions on the concert stage and in the auditorium. A similar recording was made in an anechoic space used for acoustical measurements on pianos. High speed level recordings of the magnetic tape output reveal significant differences in scale balance at the various positions. Spectrum analyses of selected tones were also recorded vs time for the different microphone locations. The recordings show that room reverberation greatly affects the tone‐wave envelope and that piano directional characteristics influence the spectrum of the tone to a limited extent.

A Mechanical Playing Device for Brass Wind Instruments

For an investigation of the steady state performance of a musical instrument, it is desirable to have a mechanical means of playing it. Human variables influencing test conditions are thus reduced, and the tone produced will be reasonably constant in intensity, quality and frequency. Brass instruments require a mechanical lip which, when driven by normal blowing pressures, will vibrate in the conventional frequency range in much the same manner as the musicians lip does. Apparatus has been constructed to try to reproduce the physical playing system fairly closely. A simple means of controlling the tension given to the lips by the surrounding muscle has been tried with some success. A short demonstration is contemplated.