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FONIX FP35 Quick Reference Guide
4.2.5 Placing the Sound Field Speaker
The placement of the sound field speaker can have a big influence on the
accuracy and repeatability of your real-ear measurements. Research has shown
that a consistent placement of 45 degrees azimuth to the client produces the
most repeatable testing results. Some clinicians, however, prefer to use the more
traditional 0 degrees azimuth to the client. See Figure 4.2.1 for a diagram of a client
being tested at 45 degrees azimuth.
In both instances, we recommend a distance of 12–15 inches from the speaker to the
client. A larger distance might make the FP35 analyzer unable to produce a 90 dB
SPL signal to the client. A small distance might place the client in an unstable place
in the field of the speaker.
You can specify which azimuth you are using for your real-ear measurements. This
will have an effect on the real-ear targets.
To set the position of the speaker:
1. Press [MENU] in any real-ear measurement screen or in the Audiogram Entry
screen.
2. Use [
5
,
6
] to select SOUND FIELD.
3. Use [
3
,
4
] to select 0º or 45º.
4. Press [EXIT] to return to the real-ear screen.
Notes:
• If you took your audiometric measurements with a sound field speaker, it is
recommended that you use the same azimuth for the real-ear measurements as
you used in the audiometric assessment.
• The speaker position is set when the sound field is leveled. If you want to
change the speaker position after leveling, you must re-level the sound field
speaker for the change to take effect.
• The leveling status will reflect the selected sound field speaker azimuth. By
default, this is set to 45º.
4.2.6 Leveling the Sound Field Speaker
The leveling process measures the sound field at the client’s ear, and accounts for
inconsistencies in the testing environment. It is essential for obtaining accurate real-
ear measurements.
You must re-level the sound field for every client and for every
ear
.
The client must be in the same position for leveling and real-ear testing—you can
use either a 0º azimuth or a 45º azimuth for leveling, as long as it is consistent with
the speaker position used for the real-ear measurements.
