Visible Speech Mapping (Vspm440); About Visible Speech Mapping - Interacoustics Affinity 2.0 Additional Information

2.12 Visible speech mapping (VSPM440)

2.12.1 About visible speech mapping

Visible Speech or Speech Mapping is a term widely used amongst manuf acturers of various systems. It
covers a kind of verif ication-, f itting-, counselling- or sales tool that provides a live demonstration of the
hearing aid f eatures in a clear layout while the client is wearing the instruments. Visible Speech Mapping
addresses the complicated task of explaining clinical and technical issues to people outside audiology.
Interacoustics Visible Speech Mapping is designed to assist you in the important process of fitting and
counselling. The system merges verif ication and counselling into one screen display visualizing the SPL at
the ear drum with and without hearing aids respectively. As a result, you can match amplif ication to target
(e.g., DSL mi/o or NAL-NL1/NAL-NL2) on the aided display and at the same time show the benef it of using
hearing aids by comparing to the unaided condition. The comprehensive layout showing dynamic range,
normal hearing thresholds, and sound examples assists in the process of communicating the measurement
results and helping achieve realistic expectations.
Various speech signals can be used with Visible Speech Mapping. The signal can be generated using a live
microphone input f rom the client, their companion, the audiologist, or speech samples can be digitally
imported f rom other sources. For both verif ication and counselling purposes, calibrated LTASS based
speech signals such as ISTS (International Speech Test Signal) are also available. The idea is to present
unaided and aided speech inf ormation to the hearing-impaired individual.
Visible Speech Mapping is also available in the paediatric f itting. When it is not f easible to do real-ear
measures, Visible Speech Mapping can be perf ormed using the individual RECD (Real-Ear-to-Coupler
Dif f erence). Af ter measuring the RECD values, the hearing aid is positioned in the test box and verif ication,
or counselling can be perf ormed here using the same principles as f or REAR/REIG.
Visible Speech Mapping can be used in all sorts of ways. Clients have very dif ferent needs, and this section
demonstrates the options offered by the system. The clinician can then tailor the input to meet their individual
requirements.
People with hearing loss are entering a whole new world with a terminology all its own. By helping them to
absorb and understand what they need to know, Visible Speech Mapping makes counselling and verif ication
a positive experience.
Note: The Visible Speech Mapping system is based on the LTASS (Long Term Average Speech Spectrum)
and the concept of time-aligned response f or a given percentile of the distribution of short-term band sound
pressure level of the speech signal. For each f requency band, the LTASS response is the gain averaged
over the stimulus duration. Speech response is established f or a given percentile f or each 100 ms sample of
the speech stimulus. These responses are averaged over the duration of the stimulus presentation.
The system produces an estimated REAR and/or a 2cc coupler response f or the LTASS and pref erred
percentiles of the selected signal. The recommended percentiles are the 30 , 65 and 99 percentiles.
th th th
The system employs three LTASS based signals Male Speech, Female Speech, and ISTS (International
Speech Test Signal). To get at precise measure, it is highly recommended to use one of these on which the
calculations are based. However, other signals can also be employed if pref erred by the individual clinician.
Live Speech is not an option f or verif ication.
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