The Masking Level Difference is an auditory processing disorder test. It is considered a binaural interaction test sensitive to low brainstem. There are two versions available: speech or tone. Each version is sold separately; therefore, it is necessary to specify version or item number when ordering. Descriptions of both versions appear described below.
MLD Speech (verbal stimuli): This recording employs spondee words imbedded in speech spectrum noise bursts. It is in two sections; section 1 is where both the noise and the spondees are in phase, section 2 is where the noise is in phase and the spondees are 180 degrees out of phase. A release from masking is expected in the latter section.
MLD Tone (500Hz) (nonverbal stimuli): Designed and recorded by Richard Wilson, this is a short test in which both hetero- and homo-phasic trials are contained. A release from masking is expected in the heterophasic conditions.
The Masking Level Difference includes a) audio recording, and b) instructions and score from as printable pdf files. The one-page instructions contain administration, scoring, and interpretation information. Normative data is included, but it is not age-specific. Available from Auditec, Inc. Call 1-800-669-9065 (from US) or 314-416-1050 (outside the US) to order. FREE shipping within the contiguous US.
[Masking Level Difference Speech Version; Item 204; Price $123.25 USD + S&H]
[Masking Level Difference Tone Version; Item 206; Price $81.00 USD + S&H]
[NCAP Battery includes Duration Pattern Sequence-Standard, Pitch Pattern Sequence – Adult & Child Versions, Random Gap Detection Test-Standard & Expanded Versions, and Masking Level Difference-Tone Version; Item CD117-9; Price $329.75 USD+ S&H]
[ACAP Battery includes Dichotic Digits-Standard, Duration Pattern Sequence-Standard, Dichotic Word Listening Test, Masking Level Difference-Tone, NU-6 Low Pass Filtered at 750 Hz, Time Compressed Sentence Test, Random Gap Detection Test, Selective Auditory Attention Test, and Competing Sentences combined on one CD; Item CD115-9; Price $549.00 USD + S&H]