FreeHear: A New Sound-Field Speech-in-Babble Hearing Assessment Tool

Pure tone threshold audiometry is currently the standard test of hearing. However, in everyday life we are more concerned with listening to speech of moderate loudness and, specifically, listening to a particular talker against a background of other talkers. FreeHear delivers strings of three spoken digits (0-9, not 7) against a background babble via 3 loudspeakers placed in front and to either side of a listener. FreeHear is designed as a rapid, quantitative initial assessment of hearing, using an adaptive algorithm. It is designed especially for children and for testing listeners who are using hearing devices. In this first report on FreeHear, we present development considerations and protocols, and results of testing 100 children (4-13 y.o) and 23 adults (18-30 y.o.). Two of six 4 y.o. and 91% of all older children completed full testing. Speech reception threshold (SRT) for digits and noise co-located at 0o or separated by 90o both improved linearly across 4-12 y.o. by 6-7 dB, with a further 2 dB improvement for the adults. These data suggested full maturation at ~15 y.o. SRTs at 90o digits/noise separation were better by ~6 dB than SRTs co-located at 0o. This spatial release from masking did not change significantly across age. Test-retest reliability was similar for children and adults (SD of 2.05 – 2.91 dB SRT), with a mean practice improvement of 0.04 – 0.98 dB. FreeHear shows promise as a clinical test for both children and adults. Further trials in people with hearing impairment are ongoing.