Frye FONIX FP40D - Manual (Page 10)

2 FONIX FP40 Portable Hearing Aid Analyzer
Also in 1994, we introduced the FP40-D desk model analyzer. This unit is always equipped with the
real ear testing function. In order to minimize costs, the Battery Pack Option is not available on this
unit and some accessories (battery pills and monitor headset) that are standard on the FP40 are
optional with the FP40-D. Since this unit does not have a lid, a separate soft carrying case is avail-
able for those who want to carry the unit from place to place.
In 1996, we improved the sound chamber significantly. The new sound box excludes much more
ambient noise than the previous model did. It was designed to be taken out of the module and
placed on a short pole for use as a speaker for real ear measurements. The speaker is then at a
higher elevation than in the previous design and can be swiveled, allowing easy positioning for real
ear measurements.
1.3 Features & Options
This section describes many of the different features and options available on the FP40 hearing aid
analyzer
1.3.1 Composite/Digital Speech Option
In addition to pure-tone tests, the FP40 can be purchased with the Composite Option, providing
real-time measurements of hearing aids. The Composite and Digital Speech signals are complex sig-
nals made up on 79 different frequencies presented simultaneously, updating about once a second.
Besides giving instant results, these test signals often provide more realistic test results of hearing
aids than you can get using pure-tone sweeps. Aids with automatic gain control (AGC) technology
can respond unexpectedly to pure-tone sweeps, providing more amplification in the low frequen-
cies than would occur in a real-life situation. This artifact of pure-tone testing, known as “artificial
blooming,” does not occur when a complex signal, such as the composite signal, is used.
Advanced digital hearing aids with “noise suppression” have different difficulties with testing. These
aids were designed to lower their gain when in the presence of a continuous sound. Unfortunately,
this generally includes conventional test signals such as pure-tone sweeps or the standard composite
signal. Digital Speech was developed as a way to test these advanced hearing aids. Digital Speech is
very similar to the composite signal except that instead of being a continuous signal, it is an inter-
rupted signal that the aid responds to as it would respond to speech.
Digital Speech comes with two speech weightings: ANSI and ICRA. The ANSI speech weighting is
from the ANSI S3.22-1992 standard – it is the same weighting used by the standard Composite sig-
nal. The ICRA speech weighing is from a CD of sounds from multiple languages developed by the
International Collegium of Rehabilitative Audiology. It rolls off the high frequencies more rapidly
than the ANSI weighting.