Compensating cocktail party noise with binaural spatial segregation on a novel device targeting partial hearing loss Luca Giuliani 1, Sara Sansalone 2, Stefania Repetto 2, Federico Traverso 3 and Luca Brayda 1 1 Fondazione Istituto Italiano di Tecnologia, Genoa, Italy 2 Linear s.r.l, Genoa, Italy 3 DITEN - University of Genoa, Genoa, Italy 1

Outline The cocktail party problem Beamforming State of the art The Glassense system Experimental setup and protocol Data analysis and results Conclusion and future works 2

The cocktail party problem Firstly defined by Colin Cherry in 1953, consists in the trouble of perceiving speech in noisy social contests. Colin Cherry 3

The cocktail party problem Approximately one-third of people over 65 year are affected by disabling hearing loss. People suffering from hearing impairment have bigger troubles in separating acoustical sources. Hearing aids are not a solution. 4

Beamforming Also called spatial filtering, is a signal processing technique used in sensor arrays to improve the Signal to Noise Ratio (SNR) of a target source. Difference between an omnidirectional beam pattern and a focused one. In the diagram on the right a focused beamforming algorithm enhances the target sound quality. 5

State of the art Modern behind-the-ear earing aids are equipped with more then one microphone to provide directionality. The improvement depends deeply on the distance between the microphones. 6

State of the art Several solutions has been proposed in the last years, but none of them made a real breakthrough in the market yet. Hearing-aid necklace by Widrow (2001) Hearing glasses by Varibel company (available on the market since 2008) 7

State of the art There are some limitations: Existing devices are designed to substitute usual hearing aids. 8 Users forced to buy and calibrate a completely new aid. It is not comfortable to swap between classical hearing aid and the directional one.

The Glassense Spectacles equipped with two arrays of digital microphones. 9 Hearing aids wireless cooperation capabilities.

The Glassense Beam power pattern at 1kHz. The listener’s head is depicted in the middle. The sounds coming from the sides and the rear are attenuated. Directivity (black line) and white noise gain (red line) of the end-fire array. The directivity of an uniformly weighted linear array (dashed black line) is shown for comparison. 10

Is the Glassense able to increase speech intelligibility in severe noisy environments? 11

Experimental Setup Seven normal hearing subjects, age years Anechoic room Four speakers around the subject, 1m away at 0° (directly ahead), 180° (back) and ±90° Glassense audio feedback provided by earplugs The experimental setup, with a subject wearing the Glassense. 12

Experimental Setup Target signal: Lists of 10 meaningful bisyllabic unrelated words (200 in total) Reproduced by the frontal speaker 13

Experimental Setup Competing noise: Four channel registration of a cocktail-like typical acoustic background Reproduced by all the surrounding speakers (included the frontal one) 14

Experimental Protocol Target signal calibrated on the subject to reach 100% performance without noise Performance = % of correctly repeated words Trial = listen and repeat task on target words with competing noise 15

Experimental Conditions First conditions: SNR Level Target speech volume fixed Competing noise volume changed in each trial, i.e. different Signal to Noise Ratios (SNRs) Performance registered at each SNR 16

Experimental Conditions Second condition: Glassense modality Unfiltered microphones, just like common behind-the-ear (BTE) hearing aids Beamforming Frequency Invariant, less directive but more stable Beamforming Frequency Variant, more directive but slightly unstable in frequency response 17

Data Analysis Speech Reception Threshold (SRT) = SNR at which the subject correctly understand 50% of target words One-way RM ANOVA: Dependent variable = SRT Independent variable = Glassense modality 18

Data analysis and results Comparing average audiometric curves of all subjects in three conditions with different filtering methods. Stars indicate significantly different SNR values 19

Data analysis and results Beamforming performs better than unfiltered microphones. As expected, frequency variant beamforming gives the best results. Speech Reception Threshold decreased by 3.8dB (p-value = 0.008) 20

Conclusion The Glassense is a pair of intelligent glasses, able to emphasize audio speech signals in the direction of interest (in front of the person). 21

Conclusion 22 No need for ad hoc configuration based on user hearing impairment, since it is accomplished providing the signal trough the hearing aid. Easy to swap between classical hearing aid and Glassense.

Future works Assessment by hearing impaired subjects, using hearing aids 23

Thank you! Francesco Diotalevi Senior Technician Luca Brayda Team Leader Linear s.r.l. Michele Ricchetti Project Coordinator Sara Sansalone Stefania Repetto Petra Bianchi Claudio Lorini Davide Dellepiane Elio Massa Co-founding: 24

Questions? 25

Compensating cocktail party noise with binaural spatial segregation on a novel device targeting partial hearing loss 26