The effects of background noise of moderate intensity on short-term storage and processing of verbal information were analyzed in 6 to 8 year old children. In line with adult studies on "irrelevant sound effect" (ISE), serial recall of visually presented digits was severely disrupted by background speech that the children did not understand. Train noises of equal Intensity however, had no effect. Similar results were demonstrated with tasks requiring storage and processing of heard information. Memory for nonwords, execution of oral instructions and categorizing speech sounds were significantly disrupted by irrelevant speech. The affected functions play a fundamental role in the acquisition of spoken and written language. Implications concerning current models of the ISE and the acoustic conditions in schools and kindergardens are discussed.

The current guidelines for hearing aid supply in Germany employ the often criticised Freiburg monosyllabic speech test (FBE) in quiet. This test can be replaced with the monosyllabic rhyme test by von Wallenberg and Kollmeier (WaKo) in quiet and by the measurement of a speech reception threshold in an interfering noise at a moderate level (45 dB SPL) using either the Göttingen or the Oldenburg sentence test (criterion: 2 dB improvement in SNR, "signal-to-noise ratio"). This procedure was investigated in a group of 38 participants with a sensorineural hearing impairment (mild, moderate or severe hearing loss) and 11 volunteers with normal hearing. On average, comparable indications were achieved. Participants with a mild hearing loss and a selective problem with listening in interfering noise were assessed more fairly.

The feasibility to replace both parts of the Freiburg speech test by more modern test procedures could be confirmed. The comparison of both monosyllabic tests showed that a reduction in the presentation level by 20 dB for the monosyllabic rhyme test would be most appropriate to achieve on average the same results with both procedures.

The results show that both of the modern speech tests can be used as an alternative to the Freiburg speech test. Altogether the monosyllabic rhyme test leads to higher speech intelligibility than the Freiburg monosyllabic test. Therefore, a reduction of the presentation level by 15 dB is recommended if it is intended to retain the existing tables for calculating the percentage of hearing loss. Reducing the presentation level also has the advantage that measurements at 100 dB SPL are not required anymore. A level of 100 dB SPL is assessed as unpleasant by many listeners.

Using the newly introduced hearing loss for speech in noise, a suitable assessment for persons with a slight hearing loss is achieved. By integrating it into the assessment procedure additionally to the hearing loss in silence, the hearing impairment of all patients can be rated depending on their speech test results in silence and in noise. In comparison to the results obtained by the KM, the new procedure does not lead to higher values for the proposed reduction in earning capacity in general, but instead seems to be equally suitable for all groups of patients.

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