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Test DLF (Dierence Limen for Frequency)
The minimum detectable change, or dierence limen, of frequency of pure tone (DLF) is a fundamental
limit of frequency resolution and is, hence, an important criterion to examine general theories of
hearing. There have been two common ways of measuring frequency discrimination. One involves the
presentation of two successive steady tones with slightly dierent frequencies. The subject is asked
to judge whether the rst or the second had the higher frequency. The order of the tones is varied
randomly from trial to trial, and the DLF is usually taken as that frequency separation between the
pulses for which the subject achieves a certain percentage of correct responses.
A second measure uses tones which are frequency modulated (FM) at a low rate (For example:
5Hz modulation frequency with a 500-Hz carrier). Usually, two successive tones are presented, one
modulated and the other unmodulated. The amount (or depth) of modulation necessary for detection
is determined.
To set the stimuli frequency variation use F1 softkey.
To set stimuli presentation rate use F2 softkey.
To perform the test set CH1 stimulus at a comfortable level and increase the DLF percentage until the
patient can perceive the difeerence between the two frequencies. The value can be stored by pressing
STORE (20) key.
Quick SIN Test
Quick SIN is a speech-in-noise test used to quickly evaluate patient capability to understand speech in
noisy environment. This capability can not be determined through the standard speech audiometry
tests. Quick SIN should be performed on adults in addition to standard audiometric tests. It is available
only in English language and requires an optional licence to be activated.
The test is performed by submitting 6 sentences, each of them composed of 5 keywords, at a
comfortable level, while the background noise is increased. A score is calculated based on recognized
keywords, the total score assesses the patient understanding capability. Speech material is provided
on SD-Card, for an easy test execution.
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