I am Streaming in a Room

Internet Acoustics is the study of sound traveling through the Internet, treating it as an acoustical medium just like air or water. Real-time streaming of sound, something commonplace nowadays, can be exploited for its own “physics” of propagation. In a digitally-connected telecommunication world, rooms of the kind which will be described enclose remotely collaborating musicians in their own reverberated sound. The ambience which results is the product of an acoustical loop which creates room-like resonances created between internet endpoints which recirculate sound echoes on the paths between them. These are synthesized acoustical spaces engineered to resemble actual rooms and distinct from other kinds of online rooms where “room” is used metaphorically for gatherings of users participating in teleconference or chat applications. The present article describes room-like internet reverberation for local area and wide area networking, respectively named LAIR and WAIR. Aspects of the medium, algorithms used and initial musical experiments are detailed. To support these topics, the article also presents a theory of operation for jacktrip, the low-latency internet streaming software which was modified for the project

Acoustic resonances in microfluidic chips: full-image micro-PIV experiments and numerical simulations

We show that full-image micro-PIV analysis in combination with images of transient particle motion is a powerful tool for experimental studies of acoustic radiation forces and acoustic streaming in microfluidic chambers under piezo-actuation in the MHz range. The measured steady-state motion of both large 5 um and small 1 um particles can be understood in terms of the acoustic eigenmodes or standing ultra-sound waves in the given experimental microsystems. This interpretation is supported by numerical solutions of the corresponding acoustic wave equation.Comment: RevTex, 10 pages, 9 eps figures; NOTE first authors changed his name to S. Melker Hagsater in the published versio

The listening room, Camden Arts Centre

This version of The Listening Room is minimal, one microphone and two loudspeakers in the Reading Room of Camden Arts Centre, a relatively small space for this work. The Reading Room is the former entrance to the building, this entrance has been bricked over to create three highly reflective wall surfaces in the room. The room resonance is so pronounced that my usual placement of microphone and speakers would tend to fix on one pitch and stay there - to introduce more of the available frequencies from the space I left the Reading Room table in the space to allow an additional reflective element and used an asymmetric placement of loudspeakers, one at the side and one under the table

Modulation-frequency acts as a primary cue for auditory stream segregation

In our surrounding acoustic world sounds are produced by different sources and interfere with each other before arriving to the ears. A key function of the auditory system is to provide consistent and robust descriptions of the coherent sound groupings and sequences (auditory objects), which likely correspond to the various sound sources in the environment. This function has been termed auditory stream segregation. In the current study we tested the effects of separation in the frequency of amplitude modulation on the segregation of concurrent sound sequences in the auditory stream-segregation paradigm (van Noorden 1975). The aim of the study was to assess 1) whether differential amplitude modulation would help in separating concurrent sound sequences and 2) whether this cue would interact with previously studied static cues (carrier frequency and location difference) in segregating concurrent streams of sound. We found that amplitude modulation difference is utilized as a primary cue for the stream segregation and it interacts with other primary cues such as frequency and location difference

Inconsistencies in the Notions of Acoustic Stress and Streaming

Inviscid hydrodynamics mediates forces through pressure and other, typically irrotational, external forces. Acoustically induced forces must be consistent with arising from such a pressure field. The use of "acoustic stress" is shown to have inconsistencies with such an analysis and generally arise from mathematical expediency but poor overall conceptualization of such systems. This contention is further supported by the poor agreement of experiment in many such approaches. The notion of momentum as being an intrinsic property of sound waves is similarly found to be paradoxical. Through an analysis that includes viscosity and attenuation, we conclude that all acoustic streaming must arise from vorticity introduced by viscous forces at the driver or other solid boundaries and that calculations with acoustic stress should be replaced with ones using a nonlinear correction to the overall pressure field

Fast acoustic streaming in standing waves : Generation of an additional outer streaming cell

Rayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL > 1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes