Local Control of Audio Environment: A Review of Methods and Applications

Abstract

The concept of a local audio environment is to have sound playback locally restricted such that, ideally, adjacent regions of an indoor or outdoor space could exhibit their own individual audio content without interfering with each other. This would enable people to listen to their content of choice without disturbing others next to them, yet, without any headphones to block conversation. In practice, perfect sound containment in free air cannot be attained, but a local audio environment can still be satisfactorily approximated using directional speakers. Directional speakers may be based on regular audible frequencies or they may employ modulated ultrasound. Planar, parabolic, and array form factors are commonly used. The directivity of a speaker improves as its surface area and sound frequency increases, making these the main design factors for directional audio systems. Even directional speakers radiate some sound outside the main beam, and sound can also reflect from objects. Therefore, directional speaker systems perform best when there is enough ambient noise to mask the leaking sound. Possible areas of application for local audio include information and advertisement audio feed in commercial facilities, guiding and narration in museums and exhibitions, office space personalization, control room messaging, rehabilitation environments, and entertainment audio systems.

Directional Landscapes: Using Parametric Loudspeakers for Sound Reproduction in Art

“…Although sound domes, wave guides, flat panel speakers and linear arrays are all techniques conceived to direct sound (Kuutti, Leiwo, & Sepponen, 2014), in this article we shall concentrate exclusively on parametric loudspeakers, the only kind that uses ultrasonic carriers to modulate incoming signals. Table 1, by no means exhaustive, traces what we consider to be the main steps in the literature concerning parametric speakers' development and research.…”

“…In their review of directional sound in media art, Kuutti et al (2014) Only two composers seem to have paid attention to directional sound technology: the Italian Michelangelo Lupone and the Argentinian Juan Pampin. The former designed and constructed in 1999 a variably sized array of parabolic loudspeakers named holophones, to be used, for example, in Ludi multifonici (Lupone and Bianchini, 2015) installed in the Trajan's Markets in Rome.…”

Novel Approach for Industrial Noise Cancellation in Speech Using ICA-EMD with PSO

“…The noise besides degrading the signal quality has its own adverse effects on human health [6] .The noise cancellation techniques are either passive or active in nature [7,8]. The passive noise control techniques use absorbing and reflecting materials to deflect the noise from its path towards the receiver [9,10].…”

“…However, if extra IMF(s) are eliminated, the result may lead to loss of information. Hence, the number of IMF(s) with minimum spectral flatness can be optimized using an objective function: (8) Where, is reconstructed signal and k is the number of initial IMF(s) to be eliminated. If is signal filtered from high frequency noise components, the value in denominator term of equation 6 will shrink.…”

Sound Straight Ahead: Parametric Speakers in Two Soundscape Installations

“…Norris's invention remained in the back of my mind for ten years, until I eventually came up with the idea for an installation (The Soundhouse, below) that required precisely the use of a parametric speaker. When I began to explore this technology, I also realized that other (if a very few) artists had already put their hands on it, in, e. and Nik Nowak's Echo (2014) [2,3]. However, none of them really spoke about their experience with it, thereby making my first direct contact with parametric speakers an adventure full of pleasant and unexpected surprises.…”