Personal Audio Loudspeaker Array as a Complementary TV Sound System for the Hard of Hearing

Abstract

The usage of this PDF file must comply with the IEICE Provisions on Copyright. The author(s) can distribute this PDF file for research and educational (nonprofit) purposes only. Distribution by anyone other than the author(s) is prohibited. SUMMARYA directional array radiator is presented, the aim of which is to enhance the sound of the television in a particular direction and hence provide a volume boost to improve speech intelligibility for the hard of hearing. The sound radiated by the array in other directions is kept low, so as not to increase the reverberant level of sound in the listening room. The array uses 32 loudspeakers, each of which are in phase-shift enclosures to generate hypercardioid directivity, which reduces the radiation from the back of the array. The loudspeakers are arranged in 8 sets of 4 loudspeakers, each set being driven by the same signal and stacked vertically, to improve the directivity in this plane. This creates a 3D beamformer that only needs 8 digital filters to be made superdirective. The performance is assessed by means of simulations and measurements in anechoic and reverberant environments. The results show how the array obtains a high directivity in a reverberant environment. key words: personal audio, array signal processing, beamforming, hearing aid

Time Domain Optimization of Filters Used in a Loudspeaker Array for Personal Audio

“…Similarly, the vector of sampled outputs to all the control microphones of the dark zone can be written as (9) where is the matrix of impulse responses from the sources to the control points in the dark zone, with size , created in the same way as .…”

“…This array is designed to be placed close to a television, hence enhancing the audio of the television in the bright zone, particularly for hard of hearing listeners [8], [9], [10]. The array is shown in Fig.…”

“…The array is shown in Fig. 6, and consists of a planar array of sources, in which each column of loudspeakers is driven in phase as a single radiator, reducing the diffuse field energy input by increasing the vertical directivity and so reducing the effect of reflections from the ceiling and floor [9]. Each individual source of the array is placed in a phase-shift cabinet, which leads to a hypercardioid-like directivity pattern for each element, further reducing the diffuse field energy injection [30].…”

“…Previous work has considered methods to provide independent audio programs inside a common space [1], [2], to restrict the sound coming from a mobile phone [3], [4], to restrict the audio coming from a personal computer [5], [6] or to create different sound zones inside a car [7]. Another personal audio application which has also been studied is that of providing a personalized audio enhancement for hearing impaired television viewers using a miniature line array [8], [9], [10]. Such an array works in a complementary way to the TV sound system and boosts the high frequency audio levels in a certain spatial region, where the hearing impaired listeners are sat, whilst minimizing the radiation everywhere else.…”

A Unified Approach to Generating Sound Zones Using Variable Span Linear Filters

“…To minimize the distortion, the pressure matching (PM) method proposed by Poletti [4] minimizes the squared difference between the desired sound field and the reproduced sound field simultaneously in both zones. Since their introduction, ACC and PM have been used in many applications [5][6][7][8][9]. Although a number of different methods exist [10][11][12][13][14][15][16][17], including mode matching, most methods are based on ACC or PM.…”