Hearing Aid Performance Study for Different Spatial Configurations

The measure of the speech reception threshold (SRT) is a procedure to evaluate the speech intelligibility in different listening conditions. The SRT in noise is defined as the signal-to-noise ratio (SNR) needed to understand 50% of the presented sentences. The SNR is adapted based on the intelligibility score of the previous sentence. The SRT will be measured with the Oldenburg Sentence Test (OLSA), which is a standard speech intelligibility test in German. The OLSA test uses nonsense sentences with equivalent difficulty.

The ACALES will be used to determine listening effort in different situations. Speech stimuli (OLSA sentences) are either presented at different levels in a background noise with fixed level or at different distances from the listener in a quiet environment. This creates different SNRs (speech levels at the position of the listener). The listening effort is subjectively rated on a predefined 13-point categorical scale with varying difficulties (SNRs or talker distance), 1= "no effort", 7 = "moderate effort" to 13 = "extreme effort". ACALES adaptively chooses the SNRs or talker distances for each presentation on the basis of previous ratings.

The ACALES will be used to determine listening effort in different situations. The ACALES will be repeated for 3 distances and 2 conditions (SE Off vs On). The outcome is a rating on a 13 points scale, as the difficulty is fixed by the distance now.

The measure of the speech perception in % is an alternative procedure to evaluate the speech intelligibility in different listening conditions. The Speech perception is defined as % correct words out of a sentence list of 20 sentences. Initially an individual presentation level is measured using adaptive procedure to determine the level necessary to understand 50% of all presented words. Afterwards the correct word score can be obtained using this individual presentation level (reduced by 1 dB) by calculating the ratio of correct words by the number of total words.

A subjective assessment will be used to determine the subjective perception. For this purpose, a novel is either read by the tester aloud (with soft voice) or presented by a loudspeaker in a reverberant room in three different distances (2m, 4m, 8m) and in an adjacent room with door left ajar.

The subject rates his/her perception of the presented real and recorded speech using a questionnaire on the dimensions "loudness, listening effort and speech intelligibility". The subjects will rate the perception on the same scale (1- 100%) for both tested conditions (SE Off and SE On) with pencils with different colors to get either absolute and relative ratings.

The measure of the speech reception threshold (SRT) is a procedure to evaluate the speech intelligibility in different listening conditions. The SRT will be measured with the Oldenburg Sentence Test (OLSA), which is a standard speech intelligibility test in German. SRTs are measured in 3 conditions: unaided, aided with fixed directional and aided with stereo zoom.