Sound Pressure Response Research Articles

Sound radiation from a concave or a convex dome in a semi-infinite tube

A previous study [H. Suzuki and J. Tichy, J. Acoust. Soc. Am. 69, 41–49 (1981)] showed that a concave or a convex dome in an infinite baffle has radiation characteristics that are different from those of the flat piston. These results indicated that a concave or a convex dome in a lossless tube may also have different radiation characteristics than a similarly mounted flat piston. This problem was investigated using the same method as the previous studies. The results show that the farfield sound pressure response rises by about 0.5 to 0.7 dB in the frequency range ka = 2.2 to 2.8 for both concave and convex domes having the height-to-radius (a) ratio of 0.5 to 1.0. As expected, the radiation resistance increases by about 13% to 17% over the radiation resistance in the low-frequency region. The radiation reactance is very small at low frequencies but becomes comparable to the resistance at frequencies above ka = 2.5. The reactance is always negative below the cutoff frequency.

Diffraction of sound by a convex or a concave dome in an infinite baffle

In the previous paper [Suzuki and Tichy, J. Acoust. Soc. Am. 69, 41–49 (1981)] the radiation from a convex or a concave dome in an infinite baffle was discussed. This paper is concerned with the second part of the work, dealing with the diffraction of sound by a convex or a concave dome. The effect of the dome on the on‐axis sound pressure responses and directivity patterns of a concentric ring source were calculated using a least‐square error method. The representation of the sound field by the energy flow as well as the pressure distribution around the source was quite successfully used to discuss the diffraction phenomena.

Sound radiation from convex and concave domes in an infinite baffle

The sound radiation from convex and concave rigid diaphragms represented by portions of a spherical surface was investigated for the purpose of modeling a direct radiator loudspeaker. Pressure responses, radiation impedances, directivity patterns, and some other characteristics were obtained and compared with those of a circular flat diaphragm of the same radius. While the on axis pressure response of the rigid flat piston remains constant, the response of the convex dome decreases for about ka?1.0 as the height of the dome increases. The concave dome has a wide smooth peak around ka=1.5 and several peaks and dips for larger values of ka. The radiation resistance of the convex dome increases by the rate of 12 dB/oct or less up to ka=2.0 and remains constant in the higher frequency regions. On the other hand, the radiation resistance of the concave dome has its largest peak at the frequency corresponding to the peak of sound pressure response. The directivity patterns of either the convex or concave dome do not have minima with zero sound pressure and their radiation patterns are generally wider than those of the circular plate. All these results are well explained by the energy flow and pressure distribution near the radiator.

Sound radiation from convex and concave domes in an infinite baffle

The sound radiation from convex and concave rigid diaphragms represented by portions of a spherical surface was investigated for the purpose of modeling a dome loudspeaker. Pressure responses, radiation impedances, directivity patterns, and some other characteristics were obtained and compared with those of a circular flat diaphragm of the same radius. While the on‐axis pressure response of the rigid flat piston remains constant, the response of the convex dome decreases for about ka ≥ 1 as the height of the dome increases. The concave dome has a wide smooth peak around ka = 1.5 and many peaks and dips for larger values of ka. The radiation resistance of the convex dome increases by the rate of 12 dB/oct or less up to about ka = 2.0 and remains almost constant in higher frequency regions. On the other hand, the radiation resistance of the concave dome has its largest peak at the frequency corresponding to the peak of sound pressure response and shows many peaks and dips in higher frequency region. The radiation reactance of the convex dome is smooth and always positive, while the concave dome also exhibits negative reactance due to the resonance in its cavity. The directivity patterns of either the convex or concave dome do not have minima with zero sound pressure and their radiation patterns are generally wider than those of the circular plate.

Effect of the voice-coil and the surround on the vibration and the sound pressure response of the cone of loudspeaker

Effect of the voice-coil and the surround on the vibration and the sound pressure response of the cone of loudspeaker

Experimental study of impulsive sound-level response statistics in a reverberrant enclosure

Many industrial noise sources exhibit strong impulse behavior and operate in a reverberant environment. The sound pressure response to this type of source is not adequately described by steady-state formulations when the responses to successive noise impulses are nonoverlapping. An experimental study has been made to assess the influence on the pressure response of such factors as source-receiver location, amount and placement of sound absorbing material, and shielding by barriers. A spark gap serves as a controllable impulsive noise source. The measured responses are the rms sound pressure and its absolute level together with its exceedance probability distribution (EPD). The rms sound pressure relates to the total energy at the receiver while the EPD relates to the time variation of the response sound pressure level. Additionally, the EPD can be used to assess compliance with noise regulations that involve a time exposure. Results of source changes (location, impulse occurrence rate) and enclosure modifications (addition of sound absorbing material or barriers) are presented. [Work supported by NSF Grant GK 4340.]

An analysis of design conditions for a phase-inverter speaker system with a drone cone

In this paper useful design conditions for a phase-inverter speaker system with a drone cone, which realize a flat response, are given for the first time by applying the network synthesis theory to the sound-pressure transfer function of this speaker system. The design conditions are obtained in relation to the sound-pressure zero below the reproducing region for the cases of the general Butterworth and the general Chebyshev rational function characteristics, and also obtained in relation to the amount of ripple of the sound-pressure frequency response in the reproducing frequency region for the case of the general Chebyshev rational function characteristic. The effects of equivalent resistance of the box due to the absorbing material on the design conditions are also considered. The calculated sound-pressure frequency response based on the design conditions obtained agrees fairly well with the measured response. Comparison of the sound-pressure frequency response of this speaker system with those of the closed box and the bass-reflex system is also given.

Coupling between pressure and temperature amplitudes in waves of second sound in liquid helium

A very sensitive microphone suitable for acoustic measurements in liquid helium is described. With the use of it both, the pressure amplitude of second sound and the amplitude of first sound radiated from the second sound transmitter (carbon layer heater) can be detected. By a special extension of the reciprocity theory the first sound pressure response of the microphone and the second sound transmitter response can be measured. The measured pressure signals of first and second sound are compared with the results of the two-fluid theory.

Considerations in high-fidelity moving-coil earphone design

The theory of simple moving-coil earphone behavior is briefly described. Some considerations concerning the measurement of sound pressure response and harmonic distortion are mentioned, with special reference to difficulties encountered at high frequencies. Several design objectives are presented, followed by a discussion of design techniques including two new approaches: 1) the introduction of a damping grease into the air gap of the magnetic structure for increased power handling ability, smoother sound pressure response and improved transient performance near the fundamental resonance; 2) a resonant back-loading cavity for improved low-frequency performance when air leaks are present.

Earphone Sound Pressures in Ears

This paper reports measurements of the sound pressure developed at the entrance to the ear canal by several earphones, and is a continuation of work previously reported on the comparison of sound pressure responses in three earphone calibration couplers. The earphones were originally applied to the ear with a 2-kg force. The sound pressure response on the ear and the statistical reliability of the response measurements have been obtained for application forces of 2, 1.5, and 1 kg. An application force of 1.5 kg was then used to obtain earphone on ear response determinations of 14 individuals. While the data are primarily for orientation for other experiments, a statistical analysis of it has given information that may be of importance in audiometry. For earphones now commercially available, differences between individuals and ears are much greater than the experimental testing precision.

Sound Measurements and Loud-Speaker Characteristics

A brief description of the method used to measure loud-speaker response is given. The Rayleigh disk and condenser microphone are compared as sound detectors. A number of loudspeaker sound pressure response curves are shown, and interpreted in terms of pleasantness of reproduction, as determined by low-and high-frequency cut-off, smoothness of response, and tone balance. Tube overloading and the effect of loudspeaker response on its apparent accentuation or diminution is discussed. The effect of room absorption characteristics, room resonances, position of the loudspeaker in the room, and position of the listener with respect to loud-speaker on loudspeaker reproduction is explained by means of diagrams and loudspeaker response curves.