A Uni-Directional Ribbon Microphone

Abstract

Directivity has been found to be desirable in sound collecting systems to improve the ratio of direct to generally reflected sounds and to otherwise discriminate against undesirable sounds. The bi-directional ribbon microphone is a pressure gradient instrument in which the response corresponds to the velocity component in a sound wave. By using a mass controlled element the velocity of the ribbon is in phase with the velocity in a sound wave. By a suitable combination of this microphone with a pressure-operated nondirectional ribbon microphone, a uni-directional ribbon microphone is obtained. The pressure ribbon microphone is resistive controlled and the response is a measure of the pressure component in a sound wave. The velocity of the ribbon in this type of pressure microphone is in phase with the pressure. Combination of the outputs of the pressure and velocity ribbon microphones produces a uni-directional characteristic. The response as a function of the angle θ between the normal to the ribbon and the direction of propagation of the incident sound is expressed by R = R0(1 + cos θ), where R0 is the sensitivity of either the pressure or velocity microphone for θ = 0. Results with an experimental microphone utilizing these principles verify the theory with respect to the phase relations and the directional characteristics. This microphone has been found to be useful in sound motion picture recording, radio broadcasting and sound reinforcing systems where the direct sounds originate in front and undesired sounds to the rear of the microphone.

Multi-band asymmetric piezoelectric MEMS microphone inspired by the Ormia ochracea

“…Directional microphones have been investigated since the 1930s, with the first commercially produced ribbon microphone invented by Harry F. Olson et al having dimensions of about 30 cm 10 cm 6.5 cm [1]. It provided a cardioid directivity pattern and was widely used in the broadcast and recording industries.…”

Design of Planar Differential Microphone Array Beampatterns with Controllable Mainlobe Beamwidth and Sidelobe Level

“…In this case, if we want to steer the main lobe to direction θ s = 0, we can set the desired beampattern as in (30).…”

“…The concept of the DMA evolutes from the directional ribbon microphone [ 30 , 31 ] responding to the sound pressure gradient field instead of the sound pressure field. The gradient direction of the sound field is parallel with the propagating direction of the sound, and the maximum directional derivative is in the gradient direction of the sound field.…”

Microphone array beamforming based on maximization of the front-to-back ratio

“…Beamforming with microphone arrays has attracted much attention recently due to its wide range of applications, such as hands-free voice communications and human-machine interfaces (Brandstein and Ward, 2001;Benesty et al, 2008;Benesty et al, 2017). Many beamforming algorithms were developed in the literature such as the delay-and-sum (DS) beamformer (Schelkunoff, 1943), broadband beamformers based narrowband decomposition (Doclo and Moonen, 2003;Benesty et al, 2007;Capon, 1969;Frost, 1972) and nested arrays (Zheng et al, 2004;Kellermann, 1991;Elko and Meyer, 2008), modal beamformers (Torres et al, 2012;Yan et al, 2011;Koyama et al, 2016;Park and Rafaely, 2005), superdirective beamformers (Cox et al, 1986;Kates, 1993;Wang et al, 2014), and differential beamformers with differential microphone arrays (DMAs) (Elko, 2000;Elko and Meyer, 2008;Chen et al, 2014;Pan et al, 2015b;Abhayapala and Gupta, 2010;Weinberger et al, 1933;Olson, 1946;Sessler and West, 1971;Warren and Thompson, 2006). Among these, differential beamformers are now widely used in a wide spectrum of small devices such as smart speakers, smartphones, and robotics, primarily because they exhibit frequency-invariant beampatterns and can achieve high directivity factors (DFs) with small apertures.…”

“…The basic principle of DMAs can be traced back to the 1930s when directional ribbon microphones were developed (Weinberger et al, 1933;Olson, 1946). Since then, much effort has been devoted to the design and study of DMAs from different perspectives.…”