A speech-in-noise screening test for hearing loss – Evaluation of different noise types

The hard of hearing organization in Norway (HLF – Hørselshemmedes Landsforbund) is interested to make a screening test available for people to check their hearing status. After the project is completed the test can be administered from the web-pages of HLF or can be downloaded as an app for smart-phone use. Decision was made to use the last word in the Norwegian Matrix test for this test.
To evaluate the ability of the test to discern between normal hearing persons from those with hearing impairment, speech reception threshold (SRT) in noise was measured for 4 different noise types:
Noise type 1 – Stationary speech noise with HF-reduced. This is the same noise as Noise type 4, but the frequencies above 1400 Hz is reduced by 15 dB.
Noise type 2 – Amplitude modulated speech noise with HF-reduced. Noise type 1 100 % amplitude modulated with a 16 Hz sine tone.
Noise type 3 – Reverse speech with HF-reduced. Matrix sentences played backward, silent periods longer than 200 ms are deleted. 4 recordings on top of each other.
Noise type 4 – Stationary speech noise. This is masking noise in the Norwegian Matrix test.
A pilot app was developed using Matlab software to measure SRT for words in these four noise types mentioned above. Measurements were performed on two groups. Group 1 consisted 28 audiology students with normal hearing. Group 2 consisted 70 persons with varying degrees of hearing loss. Audiometry was also performed for the frequencies of 250, 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz.
The poster will present results of correlation between SRTs for different noise types and audiometric thresholds, and receiver operating characteristic curves (ROC-curves) in terms of ability of the noise types to discern hearing impaired persons from those with normal hearing.