Fondazione Istituto Italiano di Tecnologia, Genoa, Italy EVALUATION OF A COMPLEMENTARY HEARING AID FOR SPATIAL SOUND SEGREGATION Luca Giuliani1, Luca Brayda1, Sara Sansalone2, Stefania Repetto2 and Michele Ricchetti2 Fondazione Istituto Italiano di Tecnologia, Genoa, Italy 2 Linear s.r.l, 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

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

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. Limited hearing aids performance in noise.

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.

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

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. High directivity Complementary to hearing aid No need for calibration on hearing loss Cannot use head as spatial selector Not available on the market anymore Hearing-aid necklace by Widrow (2001)

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. High directivity Use head as spatial selector Substitutes hearing aid Need for calibration on personal hearing loss Hearing glasses by Varibel company (available on the market since 2008)

The Glassense Signal sent to hearing aids wireless Spectacles with two arrays of digital microphones embedded in the temples. Signal sent to hearing aids wireless

The Glassense Each temple embeds a 10 cm array of four digital microphones.

The Glassense Beam power pattern at various frequencies. The sounds coming from the sides and the rear are attenuated.

Is it possible to overcome spatial filtering limitations of traditional hearing aids to improve speech comprehension capabilities for hearing impaired people in noisy environments?

Subjects 8 subjects 6 hearing impaired 2 healthy hearing Age 59-78 years

Experimental Setup Anechoic room Four speakers around the subject, 1m away at 0° (directly ahead), 180° (back) and ±90° All subjects wore a couple of in-ear hearing aids

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

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

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

Experimental Variables Independent variable: SNR Level Target speech volume fixed Competing noise volume changed in each trial, i.e. different Signal to Noise Ratios (SNRs) Dependent variable: Performance

Experimental Conditions Hearing aids condition sounds perceived directly by hearing aids microphones.

Experimental Conditions Unfiltered condition Glassense connected to hearing aids sounds perceived by Glassense microphones, without spatial filtering

Experimental Conditions Beamforming condition Glassense connected to hearing aids sounds perceived by Glassense microphones, with spatial filtering

Data Analysis Speech Reception Threshold (SRT) SNR at which the subject correctly understand 50% of target words Obtained interpolating subjects performances

Data analysis and results Mean SRT comparison improvement of 3.3 dB in beamforming condition with respect to unfiltered improvement of 2.4 dB in beamforming condition with respect to hearing aids

Conclusion The use of Glassense can improve the performance of traditional hearing aids in noise.

Conclusion No need for calibration on hearing loss, since hearing aid is already calibrated. Easy to swap between traditional hearing aid and Glassense.

Future works Extension of experimental population Measurement of Glassense contribution with more hearing aid models Comparison with other microphone array devices

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

Questions?

EVALUATION OF A COMPLEMENTARY HEARING AID FOR SPATIAL SOUND SEGREGATION DEMO AVAILABLE! luca.giuliani@iit.it /IITGlassense @IITGlassense 1

Openings @ IIT Post-doc position Antropometric modeling for personalized sensory aids PhD position Binaural filtering techniques for augmented perception and understanding of sounds Email to: luca.brayda@iit.it