HP RM500SL manual Speechmap Technical Details, FastFacts 19.2 Speechmap stimuli

19Speechmap Technical Details

19.1Section overview

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

FastFacts 19.1: Speechmap technical details

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, 1/3rd octave band SPL, vocal effort and microphone location effects are given in the following tables for the various broad-band signals available.

FastFacts 19.2: Speechmap stimuli

0611 RM500SL User’s Guide Version 2.8 Page 84