HP RM500SL - Manual (Page 84)

0611 RM500SL User’s Guide Version 2.8 Page 84
19 Speechmap Technical Details
19.1 Section overview
FastFacts 19.1: Speechmap technical details
19.2 Speechmap stimuli
FastFacts 19.2: Speechmap stimuli
The Speechmap fitting environment provides a number of well-controlled, distinctly
different stimuli. These include three varieties of speech - standard (previously
“shaped”), female, child, ICRA noise (digitally distorted speech) and pink noise at
levels of 50 to 75 dB SPL in 5 dB steps and a tone burst at 85 or 90 dB SPL.
The two standard speech signals are by the same male talker. The spectrum has
been filtered to closely match the Cox & Moore (1988) long-term average speech
spectrum (LTASS). The ICRA noise, female and child speech signals are
presented as recorded with no spectral shaping. Live speech may also be used.
As a result of reanalysis of published data, the previous distinction between “soft”
and “average” vocal effort has been eliminated. Consequently, the speech and
ICRA signals are presented unfiltered for levels from 50 to 70 dB SPL. At 75 dB
SPL, the spectrum is filtered to represent a “loud” vocal effort. An “own voice” filter
is also available at the 75 dB SPL level. This is intended to produce a spectrum
and level at a BTE microphone location similar to that produced by the voice of an
average wearer.
A tone burst (MPO) stimulus provides 128 (changed from 64) ms bursts at 1/3
octaves with a level of 90 dB SPL in S-REM and 85 dB SPL in REM mode.
In S-REM mode, all signals are filtered to include BTE, ITE, ITC, CIC, Body
microphone location effects. The selected overall rms level is established prior to
filtering.
For fitting FM systems, the stimuli may be modified to represent the level (84 dB
SPL) and spectrum at a chest microphone location and the level (93 dB SPL) and
spectrum at a boom microphone location. These are presented in the test box in
both REM and S-REM modes.
The overall SPL, 1/3 rd octave band SPL, vocal effort and microphone location
effects are given in the following tables for the various broad-band signals
available.
Speechmap provides a variety of stimuli for the testing of non-linear hearing aids
with a range of digital processing features.
This section covers the following topics:
19.2: Speechmap stimuli 19.4: Microphone location effects
19.3: Stimulus levels 19.5: Speech signal analysis
For additional information see 24: Appendix 1: AudioNote 2.1 VERIFIT and
RM500SL Test Signals and Analysis